update workflow

Author: steve4744

.github/workflows/maven.yml

@@ -19,11 +19,11 @@ jobs:
 
     steps:
     - uses: actions/checkout@v3
-    - name: Set up JDK 17
+    - name: Set up JDK 21
       uses: actions/setup-java@v3
       with:
         distribution: 'adopt-hotspot'
-        java-version: 17
+        java-version: 21
 
     - name: Build with Maven
       run: mvn -B package --file pom.xml