make yarn install fail if lockfile requires changes

Author: psmithshine

.github/workflows/build.yml

@@ -18,7 +18,7 @@ jobs:
         with:
           node-version: "${{ steps.nodenv.outputs.node-version }}"
       # # Yarn will also have been installed by actions/setup-node@v1
-      - run: yarn install
+      - run: yarn install --immutable
       - run: yarn checkFormatting
       - run: yarn workspace shared build
       - run: yarn workspace server build