pyproject: add keyring to dev dependencies group

keyring module is used in tests/conftest.py::config fixture. Therefore it's
necessary for the tests.

Fixes: 70f4564 ("Initial commit")
Signed-off-by: Alexandr Shashkin <dutyrok@altlinux.org>

pyproject.toml

@@ -30,6 +30,7 @@ pytest-mock = "^3.9"
 pytest-randomly = "^3.12"
 pytest-xdist = { version = "^3.1", extras = ["psutil"] }
 mypy = ">=1.0.0"
+keyring = "*"
 
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