deprecated field format for `license` in pyproject.toml

[stexandev]

Describe the bug
Writing a license to a pyproject.toml creates the entry in a deprecated format.

To Reproduce
Update the license field in a pyproject.toml with somesy and then build your package with python -m build.

Expected behavior
It should create an entry with a simple string.

Traces

* Building sdist...
/tmp/build-env-1ywb0epn/lib/python3.13/site-packages/setuptools/config/_apply_pyprojecttoml.py:82: SetuptoolsDeprecationWarning: `project.license` as a TOML table is deprecated
!!

        ********************************************************************************
        Please use a simple string containing a SPDX expression for `project.license`. You can also use `project.license-files`. (Both options available on setuptools>=77.0.0).

        By 2026-Feb-18, 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/guides/writing-pyproject-toml/#license for details.
        ********************************************************************************

!!

Environment

• python==3.13.5
• somesy==0.7.3
• build==1.2.2.post1

Additional context
Add any other context about the problem here.