build: Java version 21

- Changed Java version for build actions

Author: h-man2

.github/workflows/maven.yml

@@ -12,7 +12,7 @@ jobs:
 
     steps:
     - uses: actions/checkout@v3
-    - name: Set up JDK 15
+    - name: Set up JDK
       uses: actions/setup-java@v3
       with:
         java-version: '21'