Update Read the Docs configuration file

Specifying the OS is now required.

Author: jlaine

.readthedocs.yml .readthedocs.yaml

@@ -1,9 +1,12 @@
 version: 2
-formats:
-  - pdf
+
+build:
+  os: ubuntu-22.04
+  tools:
+    python: "3.12"
+
 python:
-  version: 3.8
   install:
-    - requirements: requirements/doc.txt
     - method: pip
       path: .
+    - requirements: requirements/doc.txt