Drop rails 6.1/7.0 and ruby 3.0/3.1 support

[modosc]

note: this depends on #1515

this pr removes support for:

• rails 6.1
• rails 7.0
• ruby 3.0
• ruby 3.1

all of which are will be EOL'd by 2025-04-01.

Check the following boxes:

• Wrote good commit messages.
• Feature branch is up-to-date with master (if not - rebase it).
• Squashed related commits together.
• Added tests.
• Added an entry to the Changelog if the new
  code introduces user-observable changes.
• The PR relates to only one subject with a clear title
  and description in grammatically correct, complete sentences.