Use JDK 21 for eclipse tests

.github/workflows/ant.yml

@@ -119,10 +119,10 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v4
         
-      - name: Set up JDK 17
+      - name: Set up JDK 21
         uses: actions/setup-java@v4
         with:
-          java-version: 17
+          java-version: 21
           distribution: 'zulu'
 
       - name: Cache dependencies