Update ci.yml

Author: clarkdo

.github/workflows/ci.yml

@@ -25,5 +25,5 @@ jobs:
       uses: actions/setup-node@v2
       with:
         node-version: ${{ matrix.node-version }}
-    - run: npm ci
-    - run: npm run eslint .
+    - run: yarn install --frozen-lockfile
+    - run: yarn eslint .