move the loop check of separated list to cover both parsers

[Geal]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 61.50%. Comparing base (83cfb17) to head (c4a6f52).

Files	Patch %	Lines
src/multi/mod.rs	66.66%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1756      +/-   ##
==========================================
+ Coverage   61.47%   61.50%   +0.03%     
==========================================
  Files          24       24              
  Lines        2951     2951              
==========================================
+ Hits         1814     1815       +1     
+ Misses       1137     1136       -1     

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[codspeed-hq]

CodSpeed Performance Report

Merging #1756 will not alter performance

_{Comparing separated-list-loop-check (c4a6f52) with main (83cfb17)}

Summary

✅ 24 untouched benchmarks