License metadata issues

[Kyle-Neale]

Description

We have license validations we perform on dependencies we're shipping and prometheus-client has changed. The license metadata looks bungled going from 0.21.1 to 0.22.0.

• https://pypi.org/pypi/prometheus-client/0.21.1/json
• https://pypi.org/pypi/prometheus-client/0.22.0/json

[csmarchbanks]

Hello, yes the packaging did change a bit following the move from setup.py to pyproject.toml. Currently it is following PEP 621, which allows specifying the entire license file: https://peps.python.org/pep-0621/#license. However, that was recently deprecated and we should probably move to license expressions instead. Either way, that will be a bit of a change from 0.21.x and earlier as the best practices for including licenses has changed.

I have created #1111 to move to the most recent guidance, I don't know what your parsing looks for today but it would need to parse the license_expression json field moving forward.