ci: remove --no-audit from phpunit workflow

[josephfusco]

phpunit.yml was missed in #199 and still carries --no-audit, which does not exist on the Composer version the pinned setup-php SHA installs. The advisory is already suppressed via audit.ignore in composer.json.

AI Tools

Model(s): Claude Sonnet 4.6
Used for: Drafting and implementation

[github-actions]

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 44.15%. Comparing base (d009a97) to head (a06e01b).
⚠️ Report is 13 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #200      +/-   ##
============================================
- Coverage     44.21%   44.15%   -0.07%     
- Complexity      165      170       +5     
============================================
  Files            15       15              
  Lines          1868     1889      +21     
============================================
+ Hits            826      834       +8     
- Misses         1042     1055      +13     

Flag	Coverage Δ
phpunit	44.15% <ø> (-0.07%)	⬇️

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