Fix percent-encoded username/password decoding for Basic Auth (#1623)

[MariaCodesXoXo]

Problem
HTTPie fails to decode percent-encoded characters in the username/password when they are included in the URL.
For example:
bash
http https://u%40d:1%3d2%3f@httpbin.org/basic-auth/u%40d/1%3d2%3f
returns a 401 Unauthorized.

reproduction specifications
OS: windows 11
pip version 25.3
python version 3.14
http version 3.2.4
steps followed to reproduce:
windows button and write cmd
in the command line window write : pip install httpie
in the HTTPie command run: http https://u%40d:1%3d2%3f@httpbin.org/basic-auth/u%40d/1%3d2%3f
result as shown in the screenshot:

run http --debug https://u%40d:1%3d2%3f@httpbin.org/basic-auth/u%40d/1%3d2%3f
to show details according to issue steps :

expected behavior should be same as running curl https://u%40d:1%3d2%3f@httpbin.org/basic-auth/u%40d/1%3d2%3f
curl successful output :

unlike what's mentioned in the issue documentation using the flag --auth doesn't give the desired output either
curl decodes the unserinfo before building the authorization header and that's why it works