Update JDK version from 17 to 21 in CI workflow

Author: reda-alaoui

.github/workflows/ci.yml

@@ -14,10 +14,10 @@ jobs:
     if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name != github.event.pull_request.base.repo.full_name
     steps:
       - uses: actions/checkout@v2
-      - name: Set up JDK 17
+      - name: Set up JDK 21
         uses: actions/setup-java@v2
         with:
-          java-version: '17'
+          java-version: '21'
           distribution: 'temurin'
       - name: Build with Maven
         run: ./mvnw --batch-mode clean verify