try fixing readthedocs build (#1893)

Co-authored-by: cspotcode <cspotcode@gmail.com>

.readthedocs.yaml

@@ -5,15 +5,19 @@ version: 2
 sphinx:
   configuration: doc/conf.py
 
+build:
+  os: ubuntu-22.04
+  tools:
+    # If you change this, you also need to update .github/workflows/test.yml
+    # to make sure doc test builds run on the same version.
+    #
+    # Why 3.9?
+    #  1. It's the lowest version compatible w/ Sphinx 7.2.2, a doc build dependency
+    #  2. Better doc build accessibility for contributors who may have trouble
+    #     setting up newer Python versions (Debian, etc).
+    python: "3.9"
+
 python:
-  # If you change this, you also need to update .github/workflows/test.yml
-  # to make sure doc test builds run on the same version.
-  #
-  # Why 3.9?
-  #  1. It's the lowest version compatible w/ Sphinx 7.2.2, a doc build dependency
-  #  2. Better doc build accessibility for contributors who may have trouble
-  #     setting up newer Python versions (Debian, etc).
-  version: 3.9
   install:
     - method: pip
       path: .