fix: use correct version for gemspec/gemfile

[seuros]

In my previous pr i had a small error due to a rebasing/conflict with upstream.

This PR fixes it.

[grosser]

lmk if you find a for for CI, otherwise I'll take a look

[seuros]

before 5.20
Run options: --seed 7877\n\n# Running:\n\nE\n\nFinished in 0.001204s, 830.5648 runs/s, 0.0000 assertions/s.\n\n 1) Error:\nexplode#test_0001_explodes:\nTypeError: Timeout is not a module\n <internal:[REDACTED]>:38\n <internal:[REDACTED]>:38\n spec/cases/raise.rb:11\n\n1 runs, 0 assertions, 0 failures, 1 errors, 0 skips\n\nFocus on failing tests:\nmtest spec/cases/raise.rb:10

after 5.20
Run options: --seed 7877\n\n# Running:\n\nE\n\nFinished in 0.000983s, 1017.2941 runs/s, 0.0000 assertions/s.\n\n 1) Error:\nexplode#test_0001_explodes:\nTypeError: Timeout is not a module\n lib/maxitest/timeout.rb:9\n lib/maxitest/timeout.rb:4\n <internal:[REDACTED]>:38\n <internal:[REDACTED]>:38\n spec/cases/raise.rb:11\n\n1 runs, 0 assertions, 0 failures, 1 errors, 0 skips\n\nFocus on failing tests:\nmtest spec/cases/raise.rb:10

Output 2: The error traceback additionally includes two entries for lib/maxitest/timeout.rb before the internal Ruby files and the test file.

[grosser]

thx, I'll take another if there is maybe something wrong internally, but this is nice and green anyways :)

[grosser]

yeah with pure minitest the backtrace is also longer :/
... lots of diff in that area, seems like an accident to me but also 🤷

[grosser]

5.5.0