Cache installed dependencies during CI job

Author: Andarist

.github/workflows/main.yml

@@ -12,6 +12,8 @@ jobs:
 
       - name: Use Node.js
         uses: actions/setup-node@v2.2.0
+        with:
+          cache: 'yarn'
 
       - name: Install
         run: yarn install --frozen-lockfile