unsupported-python

This package can be used as a conditional dependency to indicate lack of support for particular versions of Python.

[project]
name = "my-test-package"
version = "1.0.0"
dependencies = [
    # package does not work on Python 3.11 and beyond
    "unsupported-python; python_version>='3.11'",
]

Installing a package which depends on unsupported-python will fail with an error message, without breaking the installation further by going back to earlier versions of said package.

To allow installation of the unsupported-python dependency, and hence any package that conditionally depends on it, set the ALLOW_UNSUPPORTED_PYTHON environment variable to any value.