CI: excludes truffel 34 with x86 macOS; adds truffel 33

Author: tisba

.github/workflows/ci.yml

@@ -21,7 +21,12 @@ jobs:
           - "macos-26-intel"
           - "ubuntu-24.04"
         ruby:
-          - "truffleruby+graalvm"
+          - "truffleruby+graalvm-33"
+          - "truffleruby+graalvm-34"
+        exclude:
+          # starting TruffleRuby 34.0.0 no longer supports Intel on macOS
+          - os: "macos-26-intel"
+            ruby: "truffleruby+graalvm-34"
 
     name: ${{ matrix.os }} - ${{ matrix.ruby }}
     runs-on: ${{ matrix.os }}