ci: test against ruby 3.3 and 3.4

[mgm702]

Why

The matrix tested a single Ruby version while the gemspec declares required_ruby_version = ">= 3.2.0". Nothing was proving the gem worked on anything newer than the one pinned version.

That gap became concrete: TroutRadar, which depends on this gem, now runs Ruby 3.4.2 in production. The gem does work there — but CI was not the thing telling us so.

Change

strategy:
  fail-fast: false
  matrix:
    ruby:
      - '3.2'
      - '3.3'
      - '3.4'

fail-fast: false so one version breaking still reports the result for the others — otherwise a 3.4 failure hides whether 3.2 and 3.3 are fine, which is the main thing a matrix is for.

The floor moved from an exact patch (3.2.0 / 3.2.2) to '3.2', which resolves to the latest 3.2.x. That matches the gemspec's >= 3.2.0 rather than pinning a patch release that ages out.

Verified locally before adding

Both new versions were run before being added to CI, so this is not asking CI to discover something untested:

Ruby 3.3.10 — 70 tests, 454 assertions, 0 failures, 0 errors | 49 files, no offenses
Ruby 3.4.2  — 70 tests, 454 assertions, 0 failures, 0 errors | 49 files, no offenses

🤖 Generated with Claude Code