Upgrade JDK to 21 to fix 'invalid source release' error

Author: HyperPenetrator

.github/workflows/android_build.yml

@@ -19,10 +19,10 @@ jobs:
         with:
           node-version: '22'
 
-      - name: set up JDK 17
+      - name: set up JDK 21
         uses: actions/setup-java@v4
         with:
-          java-version: '17'
+          java-version: '21'
           distribution: 'temurin'
           cache: gradle