Merge pull request #282 from PrivateStorageio/280.tahoe-lafs-1.17.1

default.nix

nix/sources.json

setup.cfg

src/_zkapauthorizer/_storage_server.py

src/_zkapauthorizer/tests/fixtures.py

src/_zkapauthorizer/tests/foolscap.py

src/_zkapauthorizer/tests/storage_common.py

src/_zkapauthorizer/tests/test_storage_protocol.py

src/_zkapauthorizer/tests/test_storage_server.py