Change DIF to CDMX in mx_states

[svmalvaez]

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• Prefix the country code to all fields.
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[benkonrath]

@svmalvaez Please edit the description of this PR to add a description of your change along with the relevant check box items.

[benkonrath]

The state field is 3 characters long this won't work. You'll also need to modify the tests for this change.

[jackboot7]

Would be using the three letter airport code for Ciudad de México (MEX) a fix for this?

[sebasmagri]

@jackboot7 the official abbreviation is CDMX, so it would probably need the state field to be updated.

[javier-llamas]

Also I believe it can be confusing with "Estado de México" which is a different state, I know its not very conventional but as a compromise could it be CMX ??