pyproject: drop superseded license classifiers

There is an equivalent License tag already, and uv plainly errors out
too on this one.

Signed-off-by: Yann Dirson <yann.dirson@vates.tech>

Author: ydirson

pyproject.toml

@@ -19,7 +19,6 @@ readme = "README.md"
 classifiers = [
     "Environment :: Console",
     "Development Status :: 5 - Production/Stable",
-    "License :: OSI Approved :: GNU General Public License v2 (GPLv2) or later",
     "Operating System :: POSIX :: Linux :: XenServer/XCP-ng Dom0",
     "Programming Language :: Python :: 2.7",
     "Programming Language :: Python :: 3.6",