fix(ci): download pinned Gradle for native tests

.github/workflows/ci.yml

@@ -143,14 +143,10 @@ jobs:
           channel: "stable"
           cache: true
 
-      - name: Cache Gradle
-        uses: actions/cache@v5
+      - name: Setup Gradle
+        uses: gradle/actions/setup-gradle@v5
         with:
-          path: |
-            ~/.gradle/caches
-            ~/.gradle/wrapper
-          key: gradle-${{ runner.os }}-${{ hashFiles('**/*.gradle*', '**/gradle-wrapper.properties') }}
-          restore-keys: gradle-${{ runner.os }}-
+          gradle-version: "9.6.1"
 
       - name: Install Android SDK & NDK
         run: |
@@ -182,4 +178,4 @@ jobs:
         run: echo "flutter.sdk=$FLUTTER_ROOT" > android/local.properties
 
       - name: Compile Kotlin and run native unit tests
-        run: ./android/gradlew -p android :app:compileDebugKotlin :app:testDebugUnitTest
+        run: gradle -p android :app:compileDebugKotlin :app:testDebugUnitTest