Allow upip to install from custom URLs (not just pypi.org)

[redstreet]

It would be great if upip supported private repos outside pypi.org. See private-pypi.

It looks like the code change is simple, to parameterize the website via an api like upip.set_pypi_url(), which will be used below:

micropython-lib/upip/upip.py

Line 159 in eae01bd

f = url_open("https://pypi.org/pypi/%s/json" % name)

Would you entertain a PR for this if I submitted one? Thanks!

[andrewleech]

Micropython has recently rolled out a new packaging tool called mip, for details see https://docs.micropython.org/en/latest/reference/packages.html

This supports installing packages from custom repositories.