ci: correct the pull request title linter's rationale

[josephfusco]

The comment above the title job claimed the repository takes merge commit subjects from pull request titles and cited a commit range that does not show what it said it showed.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 28.56%. Comparing base (caed206) to head (8bc3a93).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##               main     #172   +/-   ##
=========================================
  Coverage     28.56%   28.56%           
  Complexity      161      161           
=========================================
  Files            15       15           
  Lines          1817     1817           
=========================================
  Hits            519      519           
  Misses         1298     1298           

Flag	Coverage Δ
phpunit	28.56% <ø> (ø)

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