actions: gradle wrapper permissions

.github/workflows/scraper.yml

@@ -15,6 +15,8 @@ jobs:
         uses: actions/setup-java@v1
         with:
           java-version: 11
+      - name: Make gradlew executable
+        run: chmod +x ./gradlew
       - name: Assembling cache client
         run: ./gradlew :cache-client:assemble --console=plain
       - name: Assembling scraper