Update test.yml

Author: ascorbic

.github/workflows/test.yml

@@ -28,6 +28,6 @@ jobs:
           node-version: ${{ matrix.node-version }}
           check-latest: '*'
       - run: npm install -g netlify-cli
-      - run: npm ci
-      - run: cd plugin && npm ci && npm run build
+      - run: yarn
+      - run: cd plugin && yarn && npm run build
       - run: npm test