Merge pull request readthedocs#78 from readthedocs/pyup/scheduled-update-2020-06-08

pyup:  Scheduled weekly dependency update for week 23

Author: humitos

docs/requirements.txt

@@ -1,5 +1,5 @@
 sphinx==1.8.5  # pyup: ignore
-sphinx-autoapi==1.3.0
+sphinx-autoapi==1.4.0
 sphinx-rtd-theme==0.4.3
 sphinx-tabs==1.1.13
 sphinx-prompt==1.1.0