Update keyring from 20.0.0 to 21.0.0

Author: pyup-bot

dev-requirements.txt

@@ -15,7 +15,7 @@ flake8-quotes==2.1.1  # Require single quotes
 flake8==3.7.9  # Lint
 freezegun==0.3.12  # Freeze time in tests
 isort==4.3.21  # Lint imports
-keyring==20.0.0
+keyring==21.0.0
 mypy==0.761 # Type checking
 pip_check_reqs==2.0.3
 pydocstyle==5.0.1  # Lint docstrings