Poetry upgrade and related packages

["Sébastien Lerique" <sl@eauchat.org>]

Dear all,

This thread is an attempt to keep a handle on the various patches 
involved in upgrading Poetry to 1.1.4, and to ask a couple 
questions that crop up.

- Tanguy's original patch http://issues.guix.info/44077 is merged
- But python-packaging had to be downgraded again because it 
  generated too much rebuilds 
  <https://lists.gnu.org/archive/html/guix-devel/2020-12/msg00003.html>
- Tanguy submitted another patch for Poetry reducing 
  python-packaging's required version: 
  https://issues.guix.info/45003

Now, there are a couple more hiccups with other packages:
- poetry actually requires a more recent version of python-keyring 
  (>=21.2.0 instead of the current 21.0.0),
- upstream python-keyring is at 21.5.0, which requires 
  python-setuptools >= 42 (guix now has 41.0.1)
- as a sidenote, when I locally added setuptools >=42 explicitely 
  to python-keyring's native-inputs, it solved the version 
  declaration problem described here 
  <https://git.savannah.gnu.org/cgit/guix.git/tree/gnu/packages/python-xyz.scm?id=04b83678653fda3c66e600e88f54f5108290ec1c#n13228>

Question: upstream setuptools is at 50.3.2, and they have dropped 
python2 support at v45 (see 
<https://github.com/pypa/setuptools/blob/master/CHANGES.rst>). 
Should we simply upgrade to v44, or rather create alternate 
python{,2}-setuptools-44 packages? `guix refresh -l 
python2-setuptools` lists 48 dependent packages.

Happy hacking!
Sébastien