Migrate to readthedocs configuration file v2¶ (#4789)

* Copy of recommded readthedocs configuration file v2

* [ci skip] It is now requirements (not requirements_file)

.readthedocs.yml

+# https://blog.readthedocs.com/migrate-configuration-v2/
+
+version: 2
+
+build:
+  os: ubuntu-22.04
+  tools:
+    python: "3.11"
+
+sphinx:
+  configuration: docs/conf.py
+
 python:
 python:
-  version: 3
-requirements_file: docs/requirements.txt
+  install:
+  - requirements: docs/requirements.txt