Merge pull request #305 from scipp/graphviz-lower-bound

Set lower bound for graphviz

Author: jl-wynen

pyproject.toml

@@ -40,7 +40,7 @@ dynamic = ["version"]
 
 [project.optional-dependencies]
 test = [
-    "graphviz",
+    "graphviz>=0.20",
     "ipywidgets>=8.1",
     "matplotlib>=3.10.7",
     "numba>=0.59",