Fix one misspelling in changelog

[clickthisnick]

Just small typo

[codecov]

Codecov Report

Merging #5287 into master will decrease coverage by 2.56%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #5287      +/-   ##
==========================================
- Coverage   94.24%   91.67%   -2.57%     
==========================================
  Files         115      115              
  Lines       26165    26165              
  Branches     2578     2578              
==========================================
- Hits        24658    23988     -670     
- Misses       1192     1857     +665     
- Partials      315      320       +5

Impacted Files	Coverage Δ
testing/test_reports.py	10.49% <0%> (-89.51%)	⬇️
testing/test_runner_xunit.py	28.57% <0%> (-71.43%)	⬇️
testing/test_session.py	24.05% <0%> (-62.66%)	⬇️
testing/test_runner.py	34.7% <0%> (-61.18%)	⬇️
testing/test_resultlog.py	53.6% <0%> (-46.4%)	⬇️
src/_pytest/reports.py	68.96% <0%> (-26.11%)	⬇️
src/_pytest/resultlog.py	67.14% <0%> (-20%)	⬇️
testing/python/metafunc.py	80.33% <0%> (-11.95%)	⬇️
testing/test_pytester.py	54.04% <0%> (-8.1%)	⬇️
testing/python/setup_only.py	92.85% <0%> (-7.15%)	⬇️
... and 12 more

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[asottile]

thanks!