unpin pip 20.2 again

[mathause]

Another enormous PR from my side ;) unpin pip again. numpy probably fixed the issue re the name of the nightly build. But I also need to doublecheck if scipy is ok.

[keewis]

thanks for keeping an eye on this, @mathause. Unfortunately, scipy doesn't seem to have fixed their package, yet, which means that we have to wait with the merge until they do.

[max-sixty]

Another enormous PR from my side ;)

Highest value per line changed! 😀

[keewis]

it seems scipy fixed this, but their wheel building repository fails the py38 build jobs so there's no py38 manylinux wheels. We could upgrade the upstream-dev CI to py39, but unfortunately there's no stable release of numba with py39 support.

Edit: see scipy/scipy#13540 and MacPython/scipy-wheels#114

[keewis]

we upgraded upstream-dev to py39 so we should be able install scipy with the new dependency resolver again, but they currently have trouble with their wheel building repository so the wheels we install are from early March. No reason not to merge this PR, though.

Edit: never mind, it seems scipy still has version inconsistencies, even with the wheels from early March (the filename still contains the date while the metadata doesn't)

[keewis]

it seems scipy has fixed their packages. If CI passes we should be able to finally merge this.

Edit: CI says

Successfully installed numpy-1.21.0.dev0+1312.gcffb69356 pandas-1.3.0.dev0+1351.g04f9a4b10d scipy-1.7.0.dev0+810.cfb3e80

So I guess this can be merged?

[keewis]

the upstream-dev failures are the ones reported by #5077, so this is ready.

[max-sixty]

Nice! Thanks @keewis !