These are only required with older python versions, but dh_python3 doesn't understand that.

--- a/setup.py
+++ b/setup.py
@@ -92,7 +92,6 @@
     install_requires=[
         "parse >= 1.18.0; python_version >= '3.0'",
         "parse >= 1.13.1; python_version <= '2.7'",
-        "enum34; python_version < '3.4'",
         "six >= 1.15",
     ],
     tests_require=[
