Documentation

Remove :exec: role directive from ValueError in TopologicalSorter.done() docstring since docstrings are not processed as reST contents.

Linked PRs

• gh-129892: Doc: Remove unnecessary role directive in graphlib.py #129896
• [3.13] gh-129892: Doc: Remove unnecessary role directive in graphlib.py (GH-129896) #129904
• [3.12] gh-129892: Doc: Remove unnecessary role directive in graphlib.py (GH-129896) #129905