Fix incorrect data in Note API test

[glennmatthews]

Closes: #n/a

What's Changed

Something I stumbled across while working on a different issue. With the test data in the REST API NoteTest, we were passing contenttypes.contenttype as the assigned_object_type instead of dcim.site.

TODO

• Explanation of Change(s)
• Added change log fragment(s) (for more information see the documentation)
• n/a Attached Screenshots, Payload Example
• Unit, Integration Tests
• n/a Documentation Updates (when adding/changing features)
• n/a Example Plugin Updates (when adding/changing features)
• n/a Outline Remaining Work, Constraints from Design