add license version

Author: khillion

setup.py

@@ -5,6 +5,7 @@
         description='Generation of CWL programmatically. Avaible types: CommandLineTool and DockerRequirement',
         author='Kenzo-Hugo Hillion and Hervé Ménager',
         author_email='[email protected] and [email protected]',
+        license='MIT',
         keywords = ['cwl'],
         install_requires=['six', 'ruamel.yaml==0.13.13'],
         packages=["cwlgen"],