Restore open ended lockfile dep.

Author: Peter Amstutz

setup.py

@@ -37,7 +37,7 @@
     'mistune >= 0.7.3, < 0.8',
     'typing >= 3.5.2, < 3.6',
     'CacheControl >= 0.11.7, < 0.12',
-    'lockfile >= 0.9, < 0.13']
+    'lockfile >= 0.9']
 
 install_requires.append("avro")  # TODO: remove me once cwltool is
 # available in Debian Stable, Ubuntu 12.04 LTS