Set license in setup.py

Author: dolfinus

setup.py

@@ -13,6 +13,7 @@
     author="dolfinus",
     author_email="[email protected]",
     description="Use git repo data for building a version number according PEP-440",
+    license='MIT',
     long_description=long_description,
     long_description_content_type="text/markdown",
     url="https://github.com/dolfinus/setuptools-git-versioning",