Update greenlet to 1.0.0.
meinheld declares a dependency to greenlet <0.5, but according to [1]
and [2], there are no API or ABI changes leading to greenlet-1.0.0, so
it seems reasonable to drop the strict requirement. This commit
uses substituteInPlace to patch setup.py since no upstream commit has
landed in the main branch yet.
Morehover, quoting [2]:
Prior to greenlet 1.0 there were no semantic meanings attached to
greenlet versions — API and ABI regularly changed from 0.4.x
to 0.4.x+1, so their current pin doesn't make much sense anyway.
nix-review reveals few broken packages that are also broken in master.
[1] https://github.com/mopemope/meinheld/pull/123
[2] https://github.com/benoitc/gunicorn/issues/2541#issuecomment-800353993
