Add a hint when free-threaded selector is used in requires-python #16963
Description
Summary
See #16951
We should be able to suggest a resolution here
Example
error: Failed to parse: `pyproject.toml`
Caused by: TOML parse error at line 4, column 19
|
4 | requires-python = ">=3.14t"
| ^^^^^^^^^
Failed to parse version: after parsing `3.14`, found `t`, which is not part of a valid version:
>=3.14t
^^^^^^^
hint: `requires-python` cannot include a free-threaded selector, consider using `uv python pin 3.14t` instead