Revert change to License classifiers

License classifiers are deprecated but the new style needs at least setuptools v77. Not all CI workflows support that currently.

Author: neofelis2X

pyproject.toml

@@ -1,12 +1,10 @@
 [build-system]
-requires = ["setuptools>=77", "cython"]
+requires = ["setuptools", "cython"]
 build-backend = "setuptools.build_meta"
 
 [project]
 name = "Printrun"
 description = "Host software for 3D printers"
-license = "GPL-3.0-or-later"
-license-files = ["COPYING"]
 authors = [
     {name = "Kliment Yanev"},
     {name = "Guillaume Seguin"},
@@ -18,6 +16,7 @@ classifiers=[
     "Intended Audience :: End Users/Desktop",
     "Intended Audience :: Manufacturing",
     "Intended Audience :: Science/Research",
+    "License :: OSI Approved :: GNU General Public License v3 or later (GPLv3+)",
     "Operating System :: MacOS :: MacOS X",
     "Operating System :: Microsoft :: Windows",
     "Operating System :: POSIX :: Linux",