CI: Remove Ruby 3.2 from test matrix

[Copilot]

Removes Ruby 3.2 from the CI test matrix as it is no longer maintained. Dependencies are starting to remove support as well.

To ensure dragonfly and MariaDB are still tested with at least one other Ruby version, adds a Rails 7.2 + Ruby 3.3 + MariaDB + Dragonfly entry to the matrix.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.15%. Comparing base (22ffec9) to head (062bf96).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3955   +/-   ##
=======================================
  Coverage   98.15%   98.15%           
=======================================
  Files         345      345           
  Lines        8964     8964           
=======================================
  Hits         8799     8799           
  Misses        165      165           

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