Add .readthedocs.yaml

New requirement. First attempt at configuring it without reading very
much about it.

https://blog.readthedocs.com/migrate-configuration-v2/

.readthedocs.yaml

@@ -0,0 +1,24 @@
+# .readthedocs.yaml
+# Read the Docs configuration file
+# See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
+
+# Required
+version: 2
+
+# Set the version of Python and other tools you might need
+build:
+  os: ubuntu-22.04
+  tools:
+    python: "3.10"
+
+# Build documentation in the docs/ directory with Sphinx
+sphinx:
+  configuration: docs/conf.py
+
+# We recommend specifying your dependencies to enable reproducible builds:
+# https://docs.readthedocs.io/en/stable/guides/reproducible-builds.html
+python:
+  install:
+  - requirements: docs/requirements.txt
+  - method: pip
+    path: .

docs/conf.py

@@ -54,7 +54,7 @@
 
 # General information about the project.
 project = "Django Ditto"
-copyright = "2016-22, Phil Gyford"
+copyright = "2016-23, Phil Gyford"
 author = "Phil Gyford"