Update license metadata

[JostMigenda]

From the output log when running python -m build:

/tmp/build-env-qorw2zgt/lib/python3.11/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.
        ********************************************************************************

[sybenzvi]

Reading the documentation, it looks like

license = { text = "BSD" }

in pyproject.toml needs to replaced by

license = "BSD-3-Clause"
license-files = ["LICEN[CS]E*"]

instead. Is it that easy?