ci(mypy): Turn on mypy --strict

See also: https://mypy.readthedocs.io/en/stable/command_line.html#cmdoption-mypy-strict

Author: tony

pyproject.toml

@@ -143,6 +143,7 @@ files = [
   "src",
   "tests"
 ]
+strict = true
 
 [[tool.mypy.overrides]]
 module = [