Revert "bump python version for readthedocs"

This reverts commit 294170a.

Author: Andrey1994

.readthedocs.yml

@@ -8,7 +8,7 @@ version: 2
 build:
   os: ubuntu-22.04
   tools:
-    python: "3.9"
+    python: "3.8"
     # You can also specify other tool versions:
     # nodejs: "20"
     # rust: "1.70"
@@ -32,4 +32,4 @@ formats:
 # See https://docs.readthedocs.io/en/stable/guides/reproducible-builds.html
 python:
   install:
-  - requirements: docs/requirements.txt
+  - requirements: docs/requirements.txt