Added cache for composer in github actions

Author: ezimuel

.github/workflows/test.yml

@@ -37,6 +37,17 @@ jobs:
       with:
         stack-version: ${{ matrix.es-version }}
 
+    - name: Get composer cache directory
+      id: composercache
+      run: echo "::set-output name=dir::$(composer config cache-files-dir)"
+      
+    - name: Cache dependencies
+      uses: actions/cache@v2
+      with:
+        path: ${{ steps.composercache.outputs.dir }}
+        key: ${{ runner.os }}-composer-${{ hashFiles('**/composer.json') }}
+        restore-keys: ${{ runner.os }}-composer-
+
     - name: Install dependencies
       run: |
         composer install --prefer-dist