Update python-screed

Hello,

Since I unfortunately couldn't participate in the sprint due to technical r=
easons, I arranged with Andreas to support you with maintaining the Python =
packages.
I started with python-screed.
Because this package required not only an upstream update but also extensiv=
e modifications, I've uploaded it to my Salsa server first:

https://salsa.debian.org/karso/python-screed

The current version builds and tests flawlessly both locally and on the Sal=
sa CI using autopkgtest.
Could someone from the team review and approve the changes?
After your approval, I would upload it to the team Salsa namespace, and a D=
D would then need to upload it.

Best regards, Karsten