Fix flake8 violations in ENUMPOLY_STRATEGY_CASES test cases

[Copilot]

PR #969 introduced ENUMPOLY_STRATEGY_CASES in tests/test_nash.py with several flake8 violations that broke the CI flake8 job.

Description of the changes in this PR

• E501 — Wrapped two over-long comment lines (115 and 146 chars) across two lines to stay within the 99-char limit
• W291 — Removed trailing whitespace from list-item continuation lines
• E128 — Fixed under-indented list continuation lines to use proper visual indent alignment
• Consistency — Normalised expected=[...] list indentation in test_enumpoly_strategy_2 and test_enumpoly_strategy_4 to match the 4-level (16-space) indent used elsewhere in the file

How to review this PR

• Review the diff in tests/test_nash.py — changes are formatting-only with no logic alterations
• Confirm flake8 . passes cleanly from the repo root