We do not need universal wheels now that we do not support python 2.

Remove the universal wheel configuration.

setup.cfg

@@ -1,9 +1,6 @@
 [metadata]
 license_file = LICENSE
 
-[bdist_wheel]
-universal=1
-
 [tool:pytest]
 testpaths=jupyterlab/tests
 norecursedirs=node_modules .git _build