Update build script to Java 21

Author: tastybento

.github/workflows/build.yml

@@ -14,11 +14,11 @@ jobs:
       - uses: actions/checkout@v3
         with:
           fetch-depth: 0  # Shallow clones should be disabled for a better relevancy of analysis
-      - name: Set up JDK 17
+      - name: Set up JDK 21
         uses: actions/setup-java@v3
         with:
           distribution: 'adopt'
-          java-version: 17
+          java-version: 21
       - name: Cache SonarCloud packages
         uses: actions/cache@v3
         with: