Fix IndexError on sparse vertex ids in kahns_algorithm_topo

[SAY-5]

Describe your change:

Fixes #15071. topological_sort used a list sized to len(graph) for indegree tracking, which assumes vertex ids are contiguous integers starting at 0. Graphs with sparse ids (e.g. {10: [20], 20: []}) crashed with IndexError. Switched indegree to a dict keyed by the actual vertex ids, and switched the queue to collections.deque so popleft() is O(1) instead of list.pop(0).

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• Add or change doctests? -- Note: Please avoid changing both code and tests in a single pull request.
• Documentation change?

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[SAY-5]

Upstream already landed this in #15076, so closing this one.