Update RTD config (#598)

- Build using Python 3.11
- The python.install option is now deprecated and replaced by build.tools.python

.readthedocs.yml

@@ -5,6 +5,12 @@
 # Required
 version: 2
 
+# Configuration for the documentation build process.
+build:
+  os: ubuntu-22.04
+  tools:
+    python: "3.11"
+
 # Build documentation in the docs/ directory with Sphinx
 sphinx:
   configuration: docs/conf.py
@@ -14,7 +20,6 @@ formats: all
 
 # Optionally set the version of Python and requirements required to build your docs
 python:
-  version: 3.8
   install:
     - requirements: docs/requirements.txt
     - method: pip