Fix pyproject.toml license

Author: vtraag

pyproject.toml

@@ -16,14 +16,13 @@ keywords=[
     "community detection",
     "clustering"
     ]
-license = {text = "GPLv3+"}
+license = "GPL-3.0-or-later"
 classifiers = [
     "Development Status :: 4 - Beta",
     "Environment :: Console",
     "Intended Audience :: End Users/Desktop",
     "Intended Audience :: Developers",
     "Intended Audience :: Science/Research",
-    "License :: GPL-3.0-or-later",
     "Operating System :: MacOS :: MacOS X",
     "Operating System :: Microsoft :: Windows",
     "Operating System :: POSIX",