Bump fakefs dependency

[faisal]

For consideration, since this has implications beyond fixing a bug:

1. This updates Rubycritic's FakeFS dependency to the 3.2.0.
2. Doing so fixes test errors we've seen in supporting Rubycritic on Ruby 4.0
3. FakeFS 3.2.0 no longer needs irb in the bundle, so remove it.
4. THIS CHANGE WILL NOT WORK ON RUBY 3.1. If we drop Ruby 3.1 support we should also pull in Remove support for Ruby 3.1 and aligned JRuby 9.4 #514 or something like it.

Check list:

• Add an entry to the changelog
• Squash all commits into a single one
• Describe your PR, link issues, etc.

[faisal]

This PR will go green once fixes/555 merges in main and so it won't have Ruby 3.1 jobs to fail in the first place.

Alternatively, I could re-PR it to main while fixes/555 continues baking.