ci: update to Java 21 for workflows

Author: quintesse

.github/workflows/ci.yml

@@ -25,10 +25,10 @@ jobs:
 
     steps:
     - uses: actions/checkout@v5
-    - name: Set up JDK 11
+    - name: Set up JDK 21
       uses: actions/setup-java@v5
       with:
-        java-version: '11'
+        java-version: '21'
         distribution: 'temurin'
         cache: maven
     - name: Build with Maven

.github/workflows/release.yml

@@ -28,10 +28,10 @@ jobs:
         with:
           fetch-depth: 0
 
-      - name: Set up JDK 11
+      - name: Set up JDK 21
         uses: actions/setup-java@v5
         with:
-          java-version: '11'
+          java-version: '21'
           distribution: 'temurin'
           cache: maven