Apply updates from cookiecutter

This automated commit applies the latest updates from our cookiecutters [1] to
this repo.

[1]: https://github.com/hypothesis/cookiecutters

pyproject.toml

@@ -60,6 +60,10 @@ show_missing = true
 precision = 2
 fail_under = 100.00
 skip_covered = true
+exclude_also = [
+    # `if TYPE_CHECKING:` blocks are only executed while running mypy.
+    "if TYPE_CHECKING:",
+]
 
 [tool.isort]
 multi_line_output = 3