Feature: support inspection of test.pypi.org packages

[miketheman]

As a way to examine packages that have been uploaded to test.pypi.org as well.

Some folks may only upload their packages to the test server, and ask users to install from test.pypi.org via chats with specific pip commands.

Currently inspector will show a 404 for any package on test.pypi.org as it only supports retrieval from the production index.

inspector/inspector/main.py

Line 57 in cfd7b09

resp = requests.get(f"https://pypi.org/pypi/{project_name}/json")

I’m not sure if this should manifest as a separate test-inspector instance and differ via config, or if there’s another way we should support test retrieval like a specific header/query string.