Add workaround for setuptools metadata format bug

Works around pypa/setuptools#4759 by excluding license files entirely, and instead relying on getting that information from trove classifiers. This fix isn't great, but will probably be overwritten very soon by cookiecutter-snekpack switching over to uv's build backend.

{{cookiecutter.package_name}}/pyproject.toml

@@ -87,6 +87,12 @@ Documentation = "https://{{cookiecutter.package_name}}.readthedocs.io"
 
 [tool.setuptools]
 package-dir = { "" = "src" }
+# This fix is here as a final tombstone before getting rid of setuptools and
+# replacing with uv's build backend. It appears that the setuptools team hasn't
+# prioritized fixing the fully breaking bug in metadata emission described in
+# https://github.com/pypa/setuptools/issues/4759. Luckily, the license
+# is inferred from the trove classifier for MIT license.
+license-files = []
 
 [tool.setuptools.packages.find]
 # this implicitly sets `packages = ":find"`