Handle 403, 404

[logangrado]

Update handling of 400 error codes such that:

• 403: Handle the same way as 401
• 404:
  • Attempt to find credentials from normal sources
  • Do not prompt if credentials are not found
• not_prompting:
  • Allow discovery of credentials when not prompting

Addresses #69

[logangrado]

@frostming Thanks for accepting this contribution.

Any idea how long it will be until this is picked up in PDM?

[frostming]

0.11.0 is released, you can get this feature by upgrading unearth.

[frostming]

It seems this causes a regression on some indexes that return 403 on not found. For example: https://download.pytorch.org/whl/numba/

When it fails to get that package on not found, it returns a 403 instead of 404, so that it will prompt for username and password.

The situation is complicated because some index return 403 on 401, while some return 403 on 404, that's quite unfortunate.

@logangrado