chore: release v0.4.0 (#1081)

## 🤖 New release
* `hugr`: 0.3.1 -> 0.4.0 (⚠️ API breaking changes)

### ⚠️ `hugr` breaking changes

```
--- failure inherent_method_const_removed: pub method is no longer const ---

Description:
A publicly-visible method or associated fn is no longer `const` and can no longer be used in a `const` context.
        ref: https://doc.rust-lang.org/reference/const_eval.html
       impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.31.0/src/lints/inherent_method_const_removed.ron

Failed in:
  ConstF64::new in /tmp/.tmpwo5blB/hugr/hugr/src/std_extensions/arithmetic/float_types.rs:43

--- failure struct_missing: pub struct removed or renamed ---

Description:
A publicly-visible struct cannot be imported by its prior path. A `pub use` may have been removed, or the struct itself may have been renamed or removed entirely.
        ref: https://doc.rust-lang.org/cargo/reference/semver.html#item-remove
       impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.31.0/src/lints/struct_missing.ron

Failed in:
  struct hugr::ops::constant::ExtensionValue, previously in file /tmp/.tmpq1W6bC/hugr/src/ops/constant.rs:184
```

<details><summary><i><b>Changelog</b></i></summary><p>

<blockquote>

## 0.4.0 (2024-05-20)

### Bug Fixes

- Disallow non-finite values for `ConstF64`
([#1075](#1075))
- Serialization round-trips
([#948](#948))
- [**breaking**] Combine `ConstIntU` and `ConstIntS`
([#974](#974))
- Disable serialisation tests when miri is active
([#977](#977))
- [**breaking**] Serialisation schema
([#968](#968))
- Correct constant fold for `fne`.
([#995](#995))
- [**breaking**] Serialisation fixes
([#997](#997))
- [**breaking**] OpDef serialisation
([#1013](#1013))
- NaryLogicOp constant folding
([#1026](#1026))

### Features

- Add verification to constant folding
([#1030](#1030))
- Add `Const::get_custom_value`
([#1037](#1037))
- Add serialization schema for metadata
([#1038](#1038))
- 'Replace' rewrite returns node map
([#929](#929))
- `new` methods for leaf ops
([#940](#940))
- Add `string` type and `print` function to `prelude`
([#942](#942))
- `CustomOp::extension` utility function
([#951](#951))
- [**breaking**] Add `non_exhaustive` to various enums
([#952](#952))
- Encoder metadata in serialized hugr
([#955](#955))
- [**breaking**] Bring back Value
([#967](#967))
- Add LoadFunction node ([#947](#947))
- Add From impls for TypeArg
([#1002](#1002))
- Constant-folding of integer and logic operations
([#1009](#1009))
- [**breaking**] Update serialisation schema, implement `CustomConst`
serialisation ([#1005](#1005))
- Merge basic blocks algorithm
([#956](#956))
- [**breaking**] Allow panic operation to have any input and output
wires ([#1024](#1024))

### Refactor

- [**breaking**] Rename `crate::ops::constant::ExtensionValue` =>
`OpaqueValue` ([#1036](#1036))
- Outline hugr::serialize::test
([#976](#976))
- [**breaking**] Replace SmolStr identifiers with wrapper types.
([#959](#959))
- Separate extension validation from the rest
([#1011](#1011))
- Remove "trait TypeParametrised"
([#1019](#1019))

### Testing

- Reorg OutlineCfg/nest_cfgs tests so hugr doesn't depend on algorithm
([#1007](#1007))
- Ignore tests which depend on typetag when cfg(miri)
([#1051](#1051))
- Really ignore tests which depend on typetag when cfg(miri)
([#1058](#1058))
- Proptests for round trip serialisation of `Type`s and `Op`s.
([#981](#981))
- Add a test of instantiating an extension set
([#939](#939))
- Ignore serialisation tests when using miri
([#975](#975))
- [**breaking**] Test roundtrip serialisation against strict + lax
schema ([#982](#982))
- Fix some bad assert_matches
([#1006](#1006))
- Expand test of instantiating extension sets
([#1003](#1003))
- Fix unconnected ports in extension test
([#1010](#1010))

</blockquote>


</p></details>

---
This PR was generated with
[release-plz](https://github.com/MarcoIeni/release-plz/).

---------

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Douglas Wilson <douglas.wilson@quantinuum.com>

hugr/CHANGELOG.md

@@ -1,9 +1,10 @@
 # Changelog
 
-## 0.4.0-alpha.1 (2024-05-13)
+## 0.4.0 (2024-05-20)
 
 ### Bug Fixes
 
+- Disallow non-finite values for `ConstF64` ([#1075](https://github.com/CQCL/hugr/pull/1075))
 - Serialization round-trips ([#948](https://github.com/CQCL/hugr/pull/948))
 - [**breaking**] Combine `ConstIntU` and `ConstIntS` ([#974](https://github.com/CQCL/hugr/pull/974))
 - Disable serialisation tests when miri is active ([#977](https://github.com/CQCL/hugr/pull/977))
@@ -15,6 +16,9 @@
 
 ### Features
 
+- Add verification to constant folding ([#1030](https://github.com/CQCL/hugr/pull/1030))
+- Add `Const::get_custom_value` ([#1037](https://github.com/CQCL/hugr/pull/1037))
+- Add serialization schema for metadata ([#1038](https://github.com/CQCL/hugr/pull/1038))
 - 'Replace' rewrite returns node map ([#929](https://github.com/CQCL/hugr/pull/929))
 - `new` methods for leaf ops ([#940](https://github.com/CQCL/hugr/pull/940))
 - Add `string` type and `print` function to `prelude` ([#942](https://github.com/CQCL/hugr/pull/942))
@@ -31,13 +35,18 @@
 
 ### Refactor
 
+- [**breaking**] Rename `crate::ops::constant::ExtensionValue` => `OpaqueValue` ([#1036](https://github.com/CQCL/hugr/pull/1036))
 - Outline hugr::serialize::test ([#976](https://github.com/CQCL/hugr/pull/976))
 - [**breaking**] Replace SmolStr identifiers with wrapper types. ([#959](https://github.com/CQCL/hugr/pull/959))
 - Separate extension validation from the rest ([#1011](https://github.com/CQCL/hugr/pull/1011))
 - Remove "trait TypeParametrised" ([#1019](https://github.com/CQCL/hugr/pull/1019))
 
 ### Testing
 
+- Reorg OutlineCfg/nest_cfgs tests so hugr doesn't depend on algorithm ([#1007](https://github.com/CQCL/hugr/pull/1007))
+- Ignore tests which depend on typetag when cfg(miri) ([#1051](https://github.com/CQCL/hugr/pull/1051))
+- Really ignore tests which depend on typetag when cfg(miri) ([#1058](https://github.com/CQCL/hugr/pull/1058))
+- Proptests for round trip serialisation of `Type`s and `Op`s. ([#981](https://github.com/CQCL/hugr/pull/981))
 - Add a test of instantiating an extension set ([#939](https://github.com/CQCL/hugr/pull/939))
 - Ignore serialisation tests when using miri ([#975](https://github.com/CQCL/hugr/pull/975))
 - [**breaking**] Test roundtrip serialisation against strict + lax schema ([#982](https://github.com/CQCL/hugr/pull/982))

hugr/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "hugr"
-version = "0.4.0-alpha.1"
+version = "0.4.0"
 edition = { workspace = true }
 rust-version = { workspace = true }