require graphviz for chart

Signed-off-by: Peter Hillman <[email protected]>

.github/workflows/website_workflow.yml

@@ -50,7 +50,7 @@ jobs:
       - name: Install doxygen & imagemagick
         # Need imagemagick for convert, to convert "Test Image" exrs to jpgs
         # Need openexr for exrheader
-        run: sudo apt-get install -y doxygen imagemagick openexr dot
+        run: sudo apt-get install -y doxygen imagemagick openexr graphviz
       - name: Install sphinx requirements
         run: pip3 install -r website/requirements.txt
       - name: Configure