[CI] Try introducing isort. (#3495)

docs/source/conf.py

@@ -10,10 +10,11 @@
 # add these directories to sys.path here. If the directory is relative to the
 # documentation root, use os.path.abspath to make it absolute, like shown here.
 
+import logging
 import os
 import sys
+
 from sphinx.ext import autodoc
-import logging
 
 sys.path.insert(0, os.path.abspath(os.path.join('..', '..')))