ci cleanup: rustdoc-gui-test now installs browser-ui-test

[lolbinarycat]

this removes the need for --unsafe-perm in the Dockerfile.

cc @GuillaumeGomez @Kobzol

[rustbot]

r? @Mark-Simulacrum

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[Kobzol]

Thanks, I think it's much nicer to make sure that we have a known and exact environment, than trying to guess and compare what comes from the outside world.

[Kobzol]

You can now delete the comment above, it's outdated. The version file itself can also be deleted, and rustdoc-gui-test can just hardcode the version for now, later we'll switch it to package.json.

Btw the same outdated comment is also in x86_64-gnu-miri/Dockerfile, could you please also delete it from there? Thanks.

[Kobzol]

r? @Kobzol

[rust-log-analyzer]

The job x86_64-gnu-tools failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

   Compiling rustdoc-gui-test v0.1.0 (/checkout/src/tools/rustdoc-gui-test)
error: unused import: `fs`
 --> src/tools/rustdoc-gui-test/src/main.rs:4:16
  |
4 | use std::{env, fs, io};
  |                ^^
  |
  = note: `-D unused-imports` implied by `-D warnings`
  = help: to override `-D warnings` add `#[allow(unused_imports)]`

---

error[E0308]: mismatched types
  --> src/tools/rustdoc-gui-test/src/main.rs:14:8
   |
14 |     Ok("0.21.1")
   |     -- ^^^^^^^^- help: try using a conversion method: `.to_string()`
   |     |  |
   |     |  expected `String`, found `&str`
   |     arguments to this enum variant are incorrect
   |
help: the type constructed contains `&'static str` due to the type of the argument passed