fix(wpt): avoid test/fixtures/wpt/README.md conflicts

[panva]

Refs: nodejs/node#63938

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 65.22%. Comparing base (4ea22b8) to head (bd6125d).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1094      +/-   ##
==========================================
+ Coverage   64.93%   65.22%   +0.29%     
==========================================
  Files          45       45              
  Lines        6938     6916      -22     
==========================================
+ Hits         4505     4511       +6     
+ Misses       2433     2405      -28     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.