kedifa: Require minimal version of zc.lockfile

setup.py

@@ -53,7 +53,7 @@ setup(
   install_requires=[
     'cryptography',  # for working with certificates
     'requests',  # for getter and updater
-    'zc.lockfile',  # for stateful updater
+    'zc.lockfile >= 1.4',  # for stateful updater
     'urllib3 >= 1.18',  # https://github.com/urllib3/urllib3/issues/258
     'six',  # for python 2 and 3 compatibility
     'caucase',  # provides utils for certificate management;