Issue #65: Update python version for readthedocs.

Author: MattClarkson

.readthedocs.yaml

@@ -9,7 +9,7 @@ version: 2
 build:
   os: ubuntu-22.04
   tools:
-    python: "3.8"
+    python: "3.13"
 
 # Build documentation in the docs/ directory with Sphinx
 sphinx: