Modify bundletool workflow for native image build

Added executable permission to gradlew script and removed static option from native-image build step.

.github/workflows/bundletool-native.yml

@@ -30,8 +30,9 @@ jobs:
           curl -L -o bundletool.zip https://github.com/google/bundletool/archive/refs/heads/master.zip
           unzip bundletool.zip
           mv bundletool-master bundletool-src
+          chmod +x bundletool-src/gradlew
 
-      - name: Build bundletool.jar
+      - name: Build bundletool.jar (using bundletool’s own Gradle)
         working-directory: bundletool-src
         run: |
           ./gradlew build -x test
@@ -41,7 +42,6 @@ jobs:
         run: |
           native-image \
             --no-fallback \
-            --static \
             -jar bundletool.jar \
             bundletool