Update actions to use java 21

Author: KiriCattus

.github/workflows/build_using_gradle.yml

@@ -20,7 +20,7 @@ jobs:
       - uses: actions/setup-java@v4
         with:
           distribution: 'zulu'
-          java-version: '17'
+          java-version: '21'
           check-latest: true
       - uses: burrunan/gradle-cache-action@v1
         with:

.github/workflows/release.yml

@@ -10,10 +10,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - name: Set up JDK 17
+      - name: Set up JDK 21
         uses: actions/setup-java@v4
         with:
-          java-version: 17
+          java-version: 21
           distribution: 'zulu'
           check-latest: true
       - name: Setup ENV