Remove use of Sphinx add_stylesheet() (#513)

The underlying problem in sphinx_rtd_theme has been fixed.

docs/source/conf.py

@@ -198,13 +198,3 @@
     "issue": ("https://github.com/dask/dask-jobqueue/issues/%s", "GH#"),
     "pr": ("https://github.com/dask/dask-jobqueue/pull/%s", "GH#"),
 }
-
-
-# Temporary work-around for spacing problem between parameter and parameter
-# type in the doc, see https://github.com/numpy/numpydoc/issues/215. The bug
-# has been fixed in sphinx (https://github.com/sphinx-doc/sphinx/pull/5976) but
-# through a change in sphinx basic.css except rtd_theme does not use basic.css.
-# In an ideal world, this would get fixed in this PR:
-# https://github.com/readthedocs/sphinx_rtd_theme/pull/747/files
-def setup(app):
-    app.add_stylesheet("basic.css")