Update sphinx-autobuild from 0.7.1 to 2020.9.1

Author: pyup-bot

docs/requirements.txt

@@ -5,4 +5,4 @@ sphinx-tabs==1.2.1
 sphinx-prompt==1.1.0
 sphinx-version-warning==1.1.2
 sphinx-notfound-page==0.5
-sphinx-autobuild==0.7.1
+sphinx-autobuild==2020.9.1