Restrict Mac JDKs

Author: jtulach

.github/workflows/mac.yml

@@ -31,7 +31,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        java: [ '8', '11', '17', '21' ]
+        java: [ '8', '11' ] # , '17', '21' ]
         os: [ macos-13 ]
 
     steps: