gh-40248: Fix reporting weight in yen_k_shortest_simple_paths
    
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If source equals target, and report_edge=True, report_weight=True, then
weight is not reported in yen_k_shortest_simple_paths. This PR fixes
this issue.

Fix #40247.

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### ⌛ Dependencies

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URL: #40248
Reported by: Yuta Inoue
Reviewer(s): David Coudert

Author: Release Manager