Describe the bug
A clear and concise description of what the bug/exception is. defines mypy as a hard build dependency.
But in my opinion that isn't one.

Wouldn't be better to define it as

[project]
dependencies = [
  "mypy>=1.14.1",
]

?

From my understanding mypy is just needed for quality control of the build process, but not required to e.g. install the code
from a pre-packaged source tarball or similar

To Reproduce
Try to package in a venv without mypy installed -> is rejected because of the missing dependency.
Try the same just through setup.py works