Fix typo --ignore-engine => --ignore-engines (#3270)

Author: nsavoire

.github/workflows/plugins.yml

@@ -840,7 +840,7 @@ jobs:
     steps:
       - uses: actions/checkout@v2
       - uses: ./.github/actions/node/setup
-      - run: yarn install --ignore-engine
+      - run: yarn install --ignore-engines
       - run: yarn services
       - run: yarn test:plugins
       - uses: codecov/codecov-action@v2