updated rtd config file

.readthedocs.yml

@@ -1,20 +1,16 @@
-# .readthedocs.yaml
-# Read the Docs configuration file
-# See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
-
-# Required
 version: 2
 
-# Build documentation in the docs/ directory with Sphinx
+build:
+  os: ubuntu-22.04
+  tools:
+    python: "3.11"
+
 sphinx:
    configuration: docs/source/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: 3.8
    install:
    - requirements: docs/requirements.txt