Add caching

.github/workflows/build.yml

@@ -19,6 +19,12 @@ jobs:
 
     - name: Install Packages
       run: yarn install
+      
+    - name: Cache Node Modules
+      uses: actions/cache@v1
+      with:
+        path: node_modules
+        key: $GITHUB_REF
 
     - name: Run Build
       run: yarn build