RTD: Update to Ubuntu 22 and Python 3.11

Author: amotl

.readthedocs.yml

@@ -0,0 +1,25 @@
+# .readthedocs.yml
+# Read the Docs configuration file
+
+# Details
+# - https://docs.readthedocs.io/en/stable/config-file/v2.html
+
+# 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
+
+python:
+  install:
+    - requirements: docs/requirements.txt
+
+# Optionally build your docs in additional formats such as PDF
+# formats:
+#   - pdf