Fix #7152: Use to_native_string to handle binary method names in prepare_method

[codeforge19]

Fixed a bug where byte-string methods were not being decoded correctly in models.py.
I replaced the direct conversion with to_native_string to ensure that methods like b'post' are correctly handled as "POST".

This fixes issue #7152.

[nateprewitt]

Hi @codeforge19, this change is not necessary. The code works as expected already.

>>> to_native_string(b"get".upper())  
'GET'

In the future, we'd recommend validating your changes prior to opening PRs. It's also helpful to validate there isn't already an open PR for issues as there are other similar changes posted as well.