fix: close HTTP resp body to prevent resource leak

[alexandear]

This PR fixes possible resource leaks by adding a statement that closes a response body.

From the documentation:

The caller must close the response body when finished with it

Also, see this article for a deep dive into the problem.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 83.80%. Comparing base (c68d830) to head (03f5e04).
Report is 255 commits behind head on main.

Files	Patch %	Lines
internal/pipe/discord/discord.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4857      +/-   ##
==========================================
+ Coverage   83.77%   83.80%   +0.03%     
==========================================
  Files         135      139       +4     
  Lines       13029    11233    -1796     
==========================================
- Hits        10915     9414    -1501     
+ Misses       1677     1356     -321     
- Partials      437      463      +26     

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[caarlos0]

thanks!!