Update the CI runner.

Signed-off-by: James R. Perkins <[email protected]>

Author: jamezp

.github/workflows/maven.yml

@@ -17,7 +17,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, windows-latest ]
-        java: ['8', '11', '17']
+        java: ['8', '11', '17', '21']
 
     steps:
       - uses: actions/checkout@v4