Unwanted comma typo results in code being `tuple` not `str`

[code-review-doctor]

trafficstars

Unwanted comma on line 609 results in code being set to a tuple rather than a string.

https://github.com/coderholic/django-cities/blob/c811bbbe2b509d99d2ea025fa1e7106330a90e51/cities/management/commands/cities.py#L608-L609

A comma makes it a tuple (no need for parent, all it takes is one comma).

Solution is to remove the comma from the end of the line. I can do that for you if you want?

[boldrack]

You should open a pull request since you know how to fix the issue.