Build action updated to use Java 21

Author: vogella

.github/workflows/maven.yaml

@@ -14,11 +14,11 @@ jobs:
         uses: actions/setup-java@v2
         with:
           distribution: "adopt"
-          java-version: "17"
+          java-version: "21"
 
       - name: Set up Maven
         uses: stCarolas/setup-maven@07fbbe97d97ef44336b7382563d66743297e442f # v4.5
         with:
-          maven-version: 3.9.4
+          maven-version: 3.9.8
       - name: Build with Maven
         run: mvn clean verify -Dskip.ui-tests=true