Copy license file to directory temporarily during Python build

Specifying files outside of the Python project root directory (the one containing the pyproject.toml/setup.py file), in your case the license file `../LICENSE`, is deprecated and scheduled for removal on 20 March 2026. See [packaging specs](https://packaging.python.org/en/latest/specifications/glob-patterns/).

Initially mentioned in #8731

<details><summary>Warning from setuptools</summary>

```text
/tmp/build-env-k8xazfj3/lib/python3.14/site-packages/setuptools/dist.py:483: SetuptoolsDeprecationWarning: Pattern '../LICENSE' cannot contain '..'
!!

        ********************************************************************************
        Please ensure the files specified are contained by the root
        of the Python package (normally marked by `pyproject.toml`).

        By 2026-Mar-20, you need to update your project and remove deprecated calls
        or your builds will no longer be supported.

        See https://packaging.python.org/en/latest/specifications/glob-patterns/ for details.
        ********************************************************************************

!!
  for path in sorted(cls._find_pattern(pattern, enforce_match))
```

</details> 

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