Declare dependency on pykwalify 1.6 or above, as older versions yield "Unknown key: version" rule errors.

NEWS

@@ -1,3 +1,7 @@
+1.1.12.dev0
+ * #45: Declare dependency on pykwalify 1.6 or above, as older versions yield "Unknown key: version"
+   rule errors.
+
 1.1.11
  * #25: Add "ssh_command" to configuration for specifying a custom SSH command or options.
  * Fix for incorrect /etc/borgmatic.d/ configuration path probing on macOS. This problem manifested

setup.py

@@ -1,7 +1,7 @@
 from setuptools import setup, find_packages
 
 
-VERSION = '1.1.11'
+VERSION = '1.1.12.dev0'
 
 
 setup(
@@ -32,7 +32,7 @@ setup(
         'atticmatic',
     ],
     install_requires=(
-        'pykwalify',
+        'pykwalify>=1.6.0',
         'ruamel.yaml<=0.15',
         'setuptools',
     ),