Use truffleruby release in CI

With [TruffleRuby 33 released](https://truffleruby.dev/blog/truffleruby-33-is-released) we don't need to use truffleruby-head anymore.

Author: eregon

.github/workflows/test.yml

@@ -30,9 +30,8 @@ jobs:
           - { os: windows-latest, ruby: jruby-head }
           - { os: macos-latest, ruby: jruby-head }
           - { os: ubuntu-latest, ruby: jruby-head }
-          # Needs truffleruby-head for (base) Data#initialize (which truffleruby 25.0 does not have)
-          - { os: ubuntu-latest, ruby: truffleruby-head }
-          - { os: macos-latest, ruby: truffleruby-head }
+          - { os: ubuntu-latest, ruby: truffleruby }
+          - { os: macos-latest, ruby: truffleruby }
           - { os: windows-latest, ruby: ucrt }
           - { os: windows-latest, ruby: mingw }
           - { os: windows-latest, ruby: mswin }