Update build.yml

Author: angrezichatterbox

.github/workflows/build.yml

@@ -40,7 +40,7 @@ jobs:
       - uses: actions/setup-java@v4
         with:
           distribution: 'zulu'
-          java-version: '11'
+          java-version: '21'
       - name: Build apk
         run: flutter build apk --release --no-shrink
       - uses: actions/upload-artifact@v4