fix: non-UTF-8 content-type headers

[Laerte]

Resolve #5914

Applied the proposed solution: #5914 (comment)

⚠️ Failed tests don't have anything to do with the change.

[codecov]

Codecov Report

Merging #5917 (4ad4159) into master (b50c032) will not change coverage.
The diff coverage is 100.00%.

❗ Current head 4ad4159 differs from pull request most recent head 7b49aa1. Consider uploading reports for the commit 7b49aa1 to get more accurate results

@@           Coverage Diff           @@
##           master    #5917   +/-   ##
=======================================
  Coverage   88.78%   88.78%           
=======================================
  Files         162      162           
  Lines       11175    11175           
  Branches     1817     1817           
=======================================
  Hits         9922     9922           
  Misses        966      966           
  Partials      287      287           

Impacted Files	Coverage Δ
scrapy/http/response/text.py	100.00% <100.00%> (ø)
scrapy/responsetypes.py	94.28% <100.00%> (ø)

[Gallaecio]

⚠️ Failed tests don't have anything to do with the change.

feigns suprise

[Gallaecio]

Awesome!

[wRAR]

Thanks!