chore: update license field

Author: william-silversmith

setup.cfg

@@ -8,10 +8,10 @@ author = William Silversmith
 author_email = [email protected]
 home_page = https://github.com/seung-lab/euclidean-distance-transform-3d/
 license_file = LICENSE
+licenses = LGPL-3.0-or-later
 classifier =
     Intended Audience :: Developers
     Development Status :: 5 - Production/Stable
-    License :: OSI Approved :: GNU Lesser General Public License v3 or later (LGPLv3+)
     Programming Language :: Python
     Programming Language :: Python :: 3
     Programming Language :: Python :: 3.9