Update mypy from 0.760 to 0.761

Author: pyup-bot

dev-requirements.txt

@@ -16,7 +16,7 @@ flake8==3.7.9  # Lint
 freezegun==0.3.12  # Freeze time in tests
 isort==4.3.21  # Lint imports
 keyring==20.0.0
-mypy==0.760 # Type checking
+mypy==0.761 # Type checking
 pip_check_reqs==2.0.3
 pydocstyle==5.0.1  # Lint docstrings
 pyenchant==2.0.0  # Bindings for a spellchecking sytem