A class of errors due to python 3.10: collections import

[Andreas Hasenack]

In general:

change

  from collections import <thing>

to

  from collections.abc import <thing>


This will list the culprits:
retry-autopkgtest-regressions --blocks python3-defaults --log-regex
'ImportError: cannot import name.*collections'

keras
python-furl
python-opcua
python-orderedmultidict
pythonpy
pyvo
sepp

I'm working on python-furl, python-orderedmultidict and python-fysom
(why isn't it in the list...? Hmm)