Enable truethy-bool in mypy by default

https://mypy.readthedocs.io/en/stable/error_code_list2.html#check-that-expression-is-not-implicitly-true-in-boolean-context-truthy-bool
background: pylint-dev/pylint#9502 (comment)

pyproject.toml

@@ -34,12 +34,13 @@ profile = "black"
 [tool.pylint."MESSAGES CONTROL"]
 max-line-length = 120
 
+[mypy]
+truethy-bool = True
+
 [build-system]
 requires = ["hatchling>=1.8.0", "hatch-vcs", "hatch-fancy-pypi-readme"]
 build-backend = "hatchling.build"
 
-
-
 [tool.hatch.metadata.hooks.fancy-pypi-readme]
 content-type = "text/markdown"
 fragments = [{ path = "README.md" }]