fix(ci): better lint check

Updates the lint check in CI. Since lint calls both lint:fix and
lint:check under the hood, this will catch issues in the case that the
linter and lint:fix aren't using exactly the same rules.

.circleci/config.yml

@@ -364,7 +364,7 @@ jobs:
             fi
       - run:
           name: Lint
-          command: yarn lint:check
+          command: yarn lint && git diff --exit-code
           working_directory: packages/<<parameters.package_name>>
       - run:
           name: Test