Add graphviz to ReadTheDocs dependencies

jim-easterbrook · jim-easterbrook · commit 665922d0f513 · 2024-02-14T16:40:08.000Z
It can't draw inheritance diagrams without it.
diff --git a/.readthedocs.yaml b/.readthedocs.yaml
@@ -9,6 +9,8 @@ build:
   os: ubuntu-22.04
   tools:
     python: "3.11"
+  apt_packages:
+    - graphviz
 
 # Build documentation in the "docs/" directory with Sphinx
 sphinx:
