Use modern config for maturin.

changelog.d/16394.misc

@@ -0,0 +1 @@
+Update maturin configuration.

pyproject.toml

@@ -92,6 +92,7 @@ skip_gitignore = true
 
 [tool.maturin]
 manifest-path = "rust/Cargo.toml"
+module-name = "synapse.synapse_rust"
 
 [tool.poetry]
 name = "matrix-synapse"

rust/Cargo.toml

@@ -15,6 +15,8 @@ name = "synapse"
 # tests/benchmarks.
 crate-type = ["lib", "cdylib"]
 
+# This is deprecated, see tool.maturin in pyproject.toml.
+# It is left here for compatibilty with maturin < 0.15.
 [package.metadata.maturin]
 # This is where we tell maturin where to place the built library.
 name = "synapse.synapse_rust"