mutation testing is timing out

[sandersaares]

Took 3 tries to get it under the 20 minute threshold here: https://github.com/microsoft/oxidizer/actions/runs/19562866735/job/56036798213?pr=58

Should:

• increase timeout (addressed by ci: Use explicit tool versions and action versions. #59)
• mutate only changed packages

[geeknoid]

https://mutants.rs/in-diff.html has info on running mutation testing on changed code only. If we use this mode, we probably should also setup some daily mutant run that runs over the entire code base too.