Updated RTD config

Read https://blog.readthedocs.com/use-build-os-config/

.readthedocs.yml

@@ -5,14 +5,15 @@
 # Required
 version: 2
 
+build:
+  os: ubuntu-22.04
+  tools:
+    python: "3.11"
+
 # Build documentation in the docs/ directory with Sphinx
 sphinx:
   configuration: docs/conf.py
 
 # Optionally build your docs in additional formats such as PDF
 formats:
   - pdf
-
-# Optionally set the version of Python and requirements required to build your docs
-python:
-  version: 3.7