The Forgejo authentication path had a few issues, which this change

fixes:

get_http_credentials was returning a header key as per the base

HostingServiceClient docstring, but this should have been headers.

  I've fixed both the bug in the Forgejo client as well as the incorrect

  docstring.
Some API errors don't include the url field, which was marked as

  required in the Pydantic schema.
Re-authentication ("Edit Credentials") was broken because it would

  still try to use the saved API key, resulting in an error about not

  having the "user:write" scope.

Due to the fix for the re-authentication issue, I discovered that the

HostingServiceTestCase.create_hosting_account method was aliasing

default_account_data instead of copying it, which allowed tests to

interfere with each other.

Authenticated to a new Forgejo server with both 2FA required and not.
Re-authenticated and saw that it correctly issued a new API token

  instead of getting a scope error.
Ran unit tests.