pytest-enabler is not needed to run tests.

--- portend-3.2.1/tox.ini.orig
+++ portend-3.2.1/tox.ini
@@ -8,7 +8,6 @@
 usedevelop = True
 extras =
 	test
-	enabler
 
 [testenv:diffcov]
 description = run tests and check that diff from main is covered