Inconsistent license information

[mitya57]

The source files in this repository declare that the license is GPL-3 or later:

python-proton-core/proton/session/__init__.py

Lines 6 to 9 in 53202ab

	Proton is free software: you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation, either version 3 of the License, or
	(at your option) any later version.

However, setup.py uses a GPL-3 only classifier:

python-proton-core/setup.py

Line 40 in 53202ab

"License :: OSI Approved :: GNU General Public License v3 (GPLv3)",

For GPL-3 or later the following should be used instead (see https://pypi.org/classifiers/):

License :: OSI Approved :: GNU General Public License v3 or later (GPLv3+)