Update github workflow JDK: 21 -> 23

Author: mperor

.github/workflows/gradle.yml

@@ -24,11 +24,11 @@ jobs:
 
     steps:
     - uses: actions/checkout@v4
-    - name: Set up JDK 21
+    - name: Set up JDK 23
       uses: actions/setup-java@v4
       with:
         distribution: 'oracle'
-        java-version: '21'
+        java-version: '23'
 
     # Configure Gradle for optimal use in GitHub Actions, including caching of downloaded dependencies.
     # See: https://github.com/gradle/actions/blob/main/setup-gradle/README.md