Change package_data to have LICENSE in a list

This is required by setuptools and as of a recent version fails if the
value(s) are not provided as a list or tuple of strings.

See: pypa/setuptools@8f848bd

Author: ExcaliburZero

setup.py

@@ -18,7 +18,7 @@
       ],
       include_package_data=True,
       package_data={
-          '': 'LICENSE'
+          '': ['LICENSE']
       },
 
       classifiers=[