[flake8-return] Exempt properties from explicit return rule (RET501)

[epenet]

First contribution - apologies if something is missing

Fixes #12197

[charliermarsh]

Thank you!

[codspeed-hq]

CodSpeed Performance Report

Merging #12243 will not alter performance

_{Comparing epenet:20240708-1515 (9e08538) with main (bf3d903)}

Summary

✅ 33 untouched benchmarks