fix: add build.os to RTD

.readthedocs.yml

@@ -2,15 +2,18 @@
 # Read the Docs configuration file
 # See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
 
-# Required
+# Set the version of Python and other tools you might need
 version: 2
+build:
+  os: ubuntu-22.04
+  tools:
+    python: "3.11"
 
 # Build documentation in the docs/ directory with Sphinx
 sphinx:
   configuration: docs/source/conf.py
   fail_on_warning: true
 
 python:
-  version: 3.8
   install:
     - requirements: requirements/doc.txt