Adapt test_response_decode_text_using_autodetect for chardet 6.0

[musicinmybrain]

Summary

See #3772. Version 6.0.0 of chardet detects this byte string as WINDOWS-1252, while previous versions detected ISO-8859-1. Since both are plausible (the encoded byte string decodes to the same Unicode string under either encoding), this PR adjusts the test to accept either claim.

Checklist

• I understand that this PR may be closed in case there was no previous discussion. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change. No new test required, as this fixes a test regression.
• I've updated the documentation accordingly. No documentation changes required.

[lovelydinosaur]

There's more we could say about this, though... yep. Thanks