Added the missing plus in gplv3+ for the Python packages.

python/setup.py.in

@@ -34,6 +34,6 @@ setup(
     python_requires='>=3.6',
     classifiers=[
         "Programming Language :: Python :: 3",
-        "License :: OSI Approved :: GNU General Public License v3 (GPLv3)",
+        "License :: OSI Approved :: GNU General Public License v3 or later (GPLv3+)",
     ],
 )