Add a python_type constructor (used by EncryptedType)

sqlalchemy_utils/types/phone_number.py

@@ -95,6 +95,9 @@ class PhoneNumberType(types.TypeDecorator, ScalarCoercible):
     STORE_FORMAT = 'e164'
     impl = types.Unicode(20)
 
+    def python_type(self, text):
+        return self._coerce(text)
+
     def __init__(self, country_code='US', max_length=20, *args, **kwargs):
         # Bail if phonenumbers is not found.
         if phonenumbers is None: