Remove license classifier

They are deprecated:

/usr/lib/python3.14/site-packages/setuptools/config/_apply_pyprojecttoml.py:61:
SetuptoolsDeprecationWarning: License classifiers are deprecated.
!!

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

        License :: OSI Approved :: Apache Software License

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

Author: dschwoerer

pyproject.toml

@@ -22,7 +22,6 @@ classifiers = [
     "Intended Audience :: Science/Research",
     "Intended Audience :: Education",
     "Intended Audience :: Developers",
-    "License :: OSI Approved :: Apache Software License",
     "Natural Language :: English",
     "Operating System :: POSIX :: Linux",
     "Programming Language :: Python :: 3.8",