I don't know which package includes GV GraphViz classes, but in the current Tool-DependencyAnalysis there are missing/moved methods (like #ifGraphVizAbsent:).
If you want to generate GraphViz visualizations (assuming you have GraphViz installed and binary path added in your PATH variable) you may load GraphViz from my repository.
Metacello new
smalltalkhubUser: 'hernan' project: 'GraphViz';
configuration: 'GraphViz';
version: #development;
load: 'Tools'.
In the Tools menu you will have a new entry named "Package Dependencies Browser" which you may use now.
After you clicked "Generate GraphViz file", the generated graph will be available in the dot/ directory.
It works at least on Windows.
Cheers,
Hernán