Adapt pypiFetch for "PEP 639 – Improving License Clarity with Better Package Metadata"

From [discord discussion](https://discord.com/channels/414106994996281365/414106994996281367/1278868637997858816):
"Saw that Python accepted a new PEP (Python Enhancement Proposal) regarding improving OSS License Clarity that might be of interest to the group here. Basically adopting SPDX license conventions, dedicated license locations and files, packaging format changes and some other things. We should be aware to better support Python in the future as well as possibly propose similar changes to other language ecosystems. See https://peps.python.org/pep-0639/"

Upon a cursory read, it is apparent that the license expression field will be added, while the license and classifiers will be deprecated. In order to address these issues, it is necessary to conduct a more thorough examination of the documentation and incorporate the necessary improvements.