Class 'OC_PythonDictionary' disallows secure coding.

[willwade]

Theres a problem with this and the example in the readme on 10.13

You get:

Traceback (most recent call last):
  File "test.py", line 3, in <module>
    pyNotificationCenter.notify("Test message", "Subtitle", "Show instantly", sound=True)
  File "pyNotificationCenter.py", line 22, in notify
    notification.setUserInfo_(userInfo)
objc.error: NSInvalidUnarchiveOperationException - Class 'OC_PythonDictionary' disallows secure coding. It must return YES from supportsSecureCoding.