Bump ReadTheDocs Python version to 3.8

pradyunsg · web-flow · commit 9aa6cbda47ee · 2021-04-11T20:07:49.000+01:00
Required for compatibility with the latest sphinx-inline-tabs release.
diff --git a/.readthedocs.yml b/.readthedocs.yml
@@ -5,6 +5,6 @@ sphinx:
   configuration: docs/html/conf.py
 
 python:
-  version: 3.7
+  version: 3.8
   install:
     - requirements: tools/requirements/docs.txt
