Merge pull request rails#47517 from Shopify/yarn-frozen-lockfile

Dockerfile: run yarn install with --frozen-lockfile

Author: byroot

railties/lib/rails/generators/rails/app/templates/Dockerfile.tt

@@ -43,7 +43,7 @@ RUN bundle install && \
 <% if using_node? -%>
 # Install node modules
 COPY package.json yarn.lock ./
-RUN yarn install
+RUN yarn install --frozen-lockfile
 
 <% end -%>
 # Copy application code