Fix license string

setup.py

@@ -28,7 +28,7 @@ setup(
     packages=find_packages(),
     classifiers=[
         'Programming Language :: Python :: 3',
-        'License :: OSI Approved :: GPLv3',
+        'License :: OSI Approved :: GNU General Public License v3 (GPLv3)',
         'Operating System :: OS Independent',
     ],
     python_requires='>=3.6',