[pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Author: pre-commit-ci[bot]

.readthedocs.yml

@@ -1,3 +1,4 @@
+---
 # .readthedocs.yml
 # Read the Docs configuration file
 # See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
@@ -13,6 +14,6 @@ formats:
 - pdf
 
 python:
-  version: "3.8"
+  version: '3.8'
   install:
   - requirements: requirements.txt