ci: re-enable browser check

.github/workflows/build.yml

@@ -42,9 +42,7 @@ jobs:
 
           jupyter labextension list
           jupyter labextension list 2>&1 | grep -ie "jupyterlab-myst.*OK"
-          # Temporarily allow CI to pass
-          python -c "from packaging.version import Version; from importlib.metadata import version as version_of; raise SystemExit(Version(version_of('jupyterlab')) > Version('4.0.6'))" 
-          # python -m jupyterlab.browser_check
+          python -m jupyterlab.browser_check
 
       - name: Package the extension
         run: |