fix: serialization of []http.Cookie

[youta1119]

Fixes #776

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 83.33333% with 3 lines in your changes missing coverage. Please review.

Project coverage is 93.00%. Comparing base (4977a7a) to head (001826c). Report is 5 commits behind head on main.

Files with missing lines	Patch %	Lines
huma.go	83.33%	2 Missing and 1 partial :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #778      +/-   ##
==========================================
- Coverage   93.10%   93.00%   -0.11%     
==========================================
  Files          23       23              
  Lines        5296     5301       +5     
==========================================
- Hits         4931     4930       -1     
- Misses        313      317       +4     
- Partials       52       54       +2     

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[KingkorAtMaxint]

Can this be merged and released please? This is a huge bug and it's stopping us from implement a cookie based authentication. When we try to set multiple cookies using the slices syntax, it's setting the first one as whole. Then it adds another Set-Cookie with all the cookies combined by ,