[Chore] Update ruby version used in CI to 3.3

[rvem]

Description

Explicitly pin ruby and danger versions in CI to avoid the situation when the latest danger version (which is used by the action by default) becomes incompatible with the used ruby version (due to version requirements for some transitive danger dependencies).
An example of such incompatibility: https://github.com/serokell/xrefcheck/pull/294/checks#step:4:15

Related issue(s)

Fixes #

✅ Checklist for your Pull Request

Ideally a PR has all of the checkmarks set.

If something in this list is irrelevant to your PR, you should still set this
checkmark indicating that you are sure it is dealt with (be that by irrelevance).

Related changes (conditional)

• Tests

  • If I added new functionality, I added tests covering it.
  • If I fixed a bug, I added a regression test to prevent the bug from
    silently reappearing again.

• Documentation

  • I checked whether I should update the docs and did so if necessary:
    • README
    • Haddock

• Public contracts

  • Any modifications of public contracts comply with the Evolution
    of Public Contracts policy.
  • I added an entry to the changelog if my changes are visible to the users
    and
  • provided a migration guide for breaking changes if possible

Stylistic guide (mandatory)

• My commits comply with the policy used in Serokell.
• My code complies with the style guide.

✓ Release Checklist

• I updated the version number in package.yaml.
• I updated the changelog and moved everything
  under the "Unreleased" section to a new section for this release version.
• (After merging) I edited the auto-release.
  • Change the tag and title using the format vX.Y.Z.
  • Write a summary of all user-facing changes.
  • Deselect the "This is a pre-release" checkbox at the bottom.
• (After merging) I updated xrefcheck-action.
• (After merging) I uploaded the package to hackage.