Add Rails 8.1 support

[dshyrshov]

This PR adds support for Rails 8.1 that was recently released.

As rails > 8.0 requires ruby versions >= 3.2.0 we still need to omit all lower versions in testing.

[dshyrshov]

I had to pin ruby/setup-ruby version to a commit SHA due to SonarCube warnings 😅 . It will need to be updated from time to time manually.

[iMacTia]

Thank you for opening this!

I had to pin ruby/setup-ruby version to a commit SHA due to SonarCube warnings 😅

Well, that's new... don't worry about that honestly. Just put v1 back and I'll take a look separately

[sonarqubecloud[bot]]

Quality Gate failed

Failed conditions
2 Security Hotspots

See analysis details on SonarQube Cloud

[dshyrshov]

@iMacTia Thanks! I've reverted the ruby/setup-ruby change. Please have a look 👍

[iMacTia]

Version 2.6.0 is out 🙌 !