DOC: Pin the readthedocs OS and Python version

Author: BvB93

.readthedocs.yml

@@ -7,15 +7,23 @@ version: 2
 
 # Build documentation in the docs/ directory with Sphinx
 sphinx:
-    configuration: docs/conf.py
+  configuration: docs/conf.py
+
+# Configuration for the documentation build process.
+# This allows you to specify the base Read the Docs image used to build the documentation,
+# and control the versions of several tools: Python, Node.js, Rust, and Go.
+build:
+  os: ubuntu-22.04
+  tools:
+    python: "3.11"
 
 # Optionally build your docs in additional formats such as PDF
 formats: all
 
 # Optionally set the version of Python and requirements required to build your docs
 python:
-    install:
-        - method: pip
-          path: .
-          extra_requirements:
-            - doc
+  install:
+    - method: pip
+      path: .
+      extra_requirements:
+        - doc