Update license in setup.py to GPLv3

setup.py

@@ -3,9 +3,9 @@ from setuptools import setup, find_packages
 setup(name='nafuma',
       version='0.4',
       description='Analysis tools for inorganic materials chemistry at the NAFUMA-group at the University of Oslo',
-      url='https://github.com/rasmusthog/nafuma',
+      url='https://forge.rasmusthog.me/rasmus/nafuma',
       author='Rasmus Vester Thøgersen, Halvor Høen Hval',
       author_email='code@rasmusthog.me',
-      license='MIT',
+      license='GPLv3',
       packages=find_packages(),
       zip_safe=False)