…aph_labeling.py; add colorcet dependency

…d references and usage tips

Squashed commits:
[d4850706] WIP commit: refactoring decision table graph labeling
[bd8b92de] WIP commit: refactoring decision table graph labeling
[8b70d33d] WIP commit: refactoring decision table graph labeling

This reverts commit 15c2038. (+3 squashed commits)
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[e25a0bdf] reverse graphviz
[3e034793] Revert "Add graphviz dependencies to build process"

This reverts commit eaca399.
[44a9dd26] Refactor graph labeling functions for improved clarity and error handling