ci: readthedocs

ew...

    Problem in your project's configuration. Invalid "python.version":
    expected one of (2, 2.7, 3, 3.5, 3.6, 3.7, 3.8, pypy3.5), got 3.1

Author: justinmk

.readthedocs.yml

@@ -2,5 +2,5 @@ build:
   image: latest
 
 python:
-  version: 3.10
+  version: 3.8
   setup_py_install: true