Try ubu22.04.

See if this fixes:

```
---- repo_version::tests::test_run_python_script stdout ----
thread 'repo_version::tests::test_run_python_script' panicked at ops/src/repo_version.rs:392:55:
called `Result::unwrap()` on an `Err` value: Error running version script (exit code 1; script: python version.py):

Access error: uid 1001, last mount name:/firejail/firejail.ro.file dir:/run/firejail/firejail.ro.file type:tmpfs - invalid noexec mount

note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
```

I know ubuntu 24 made some changes around sandboxing. It's possible that latest changed to 24 recently and broke this test.

https://github.blog/changelog/2024-09-25-actions-new-images-and-ubuntu-latest-changes/

> The ubuntu-latest label will migrate to Ubuntu 24 over the course of the next month, beginning September 23rd and finishing on October 30th

- bazelbuild/bazel#24081
- https://ubuntu.com/blog/ubuntu-23-10-restricted-unprivileged-user-namespaces

Author: rcorre

Diff for: .github/workflows/rust.yml

@@ -5,7 +5,7 @@ on: [push]
 jobs:
   build:
 
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
 
     steps:
     - name: Checkout sources