remove old python 3.4 conditional

setup.py

@@ -52,13 +52,6 @@ def get_static_files(path):
 else:
     install_requires.append('tornado>=5.0,<6')
 
-# Note: To support older versions of setuptools, we're explicitly not
-#   using conditional syntax (i.e. 'enum34>1.1.0;python_version<"3.4"').
-#   This syntax is a problem for setuptools as recent as `20.1.1`,
-#   published Feb 16, 2016.
-if sys.version_info[:2] < (3, 4):
-    install_requires.append('enum34>1.1.0')
-
 if os.environ.get('READTHEDOCS', None) == 'True':
     # So that we can build documentation for luigi.db_task_history and luigi.contrib.sqla
     install_requires.append('sqlalchemy')