ci: Run yarn install with the --frozen-lockfile option

Author: croutonn

.github/workflows/main.yml

@@ -20,7 +20,7 @@ jobs:
         uses: actions/[email protected]
         with:
           node-version: ${{ matrix.node-version }}
-      - name: yarn install
+      - name: yarn install --frozen-lockfile
         run: yarn install
       - name: Test code
         env: