Add rust ubuntu runner

[s34m]

Standards checklist:

• [ ] The PR title is descriptive.
• [ ] The code compiles (cargo build)
• [ ] The code passes rustfmt (cargo fmt)
• [ ] The code passes clippy (cargo clippy)
• [ ] The code passes tests (cargo test)
• [ ] Optional: I have tested the code myself
  • [ ] I also tested that Topgrade skips the step where needed

If you developed a feature or a bug fix for someone else and you do not have the means to test it, please tag this person here.