Add gradle caching.

Author: ychescale9

.github/workflows/workflow.yml

@@ -38,7 +38,13 @@ jobs:
       uses: actions/setup-java@v1
       with:
         java-version: 14
-
+    - name: Clean cache
+      if: matrix.os == 'macos-latest'
+      run: mv ~/.gradle/caches ~/.gradle/.invalid_caches
+    - uses: actions/cache@v1
+      with:
+        path: ~/.gradle/caches
+        key: ${{ runner.os }}-gradle-${{ hashFiles('**/*.gradle*') }}-${{ hashFiles('**/gradle/wrapper/gradle-wrapper.properties') }}
     - name: run action
       uses: ./
       with: