build: update to new license format in pyproject.toml

[Mause]

Fixes a number of deprecation notices during the build

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-pyproj
ect-toml/#license
      for details.                                                
      ************************************************************
********************                                                                                                                      !!
        corresp(dist, value, root_dir)
      /data/data/com.termux/files/home/.cache/uv/builds-v0/.tmpdi8
SEc/lib/python3.12/site-packages/setuptools/config/_apply_pyprojec
ttoml.py:61:
      SetuptoolsDeprecationWarning: License classifiers are
      deprecated.
      !!


      ************************************************************
********************
              Please consider removing the following classifiers
      in favor of a SPDX license expression:

              License :: OSI Approved :: MIT License

              See
      https://packaging.python.org/en/latest/guides/writing-pyproj
ect-toml/#license
      for details.