Changes

pyproject: use SPDX license identifier

Fix the following warnings during build:

!!

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

        License :: OSI Approved :: GNU General Public License v2 or later (GPLv2+)

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

!!

!!

        ********************************************************************************
        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.
        ********************************************************************************

!!

Change-Id: I8416234ea02f337fabd075cc345af964c1b71adf

Bump version: 0.0.11

Tag a new version, and this time adjust pyproject.toml too so we can
publish the new version to pypi. I'm updating the instructions in the
wiki so this is clear in the future:
https://osmocom.org/projects/cellular-infrastructure/wiki/Make_a_new_release

Change-Id: I1b5735abefbd69c0d3301b5506424800db25aec6