`nationality` method under `faker.providers.address` for locale `en_US`

[Kemystra]

First of all, thank you for this amazing tool!

I'm looking for a way to generate fake nationalities in the English language but it seems like it is not available under the en_US locale (and quite a lot of other locales actually). The only locale that provided such method is the pt_PT locale.

My questions would be:

1. Are there any specific reasons why it isn't there?
2. If there's no reason to not add them, may I try to make a pull request to add them?

[stefan6419846]

There does not seem to be a specific reason for this - #984 just introduced it for this specific locale without having a default implementation in the default locale.