Fix the maintainer email (#119)

Author: ap--

setup.cfg

@@ -9,7 +9,7 @@ license_files =
 url = https://github.com/fsspec/universal_pathlib
 platforms=any
 authors = Andrew Fulton
-maintainer_email = andrewfulton9gmail.com
+maintainer_email = andrewfulton9@gmail.com
 classifiers =
     Programming Language :: Python :: 3
     Programming Language :: Python :: 3.8