Add .readthedocs.yaml

Now required per
readthedocs/readthedocs.org#4668

Author: cxw42

.editorconfig

@@ -10,4 +10,8 @@ max_line_length = 78
 indent_size = 4
 indent_style = space
 end_of_line = lf
-max_line_length = 78
+max_line_length = 78
+
+[*.{yaml,yml}]
+indent_size = 2
+indent_style = space

.readthedocs.yaml

@@ -0,0 +1,9 @@
+version: 2
+
+build:
+  os: ubuntu-22.04
+  tools:
+    python: "3.12"
+
+sphinx:
+  configuration: conf.py