Remove NGN as default currency

[tolu-paystack]

The package currently defaults to NGN as the currency if no currency is provided to PaystackProvider. This makes it seem like Nigerian merchants are the default, and any merchants using this package outside of Nigeria have to provide an extra parameter that Nigerian merchants don't.

Paystack already uses the default currency of the merchant's integration if no currency is passed when initializing a transaction, so there's no need to include a default in the code

[just1and0]

Good point, i agree with that.
should have this in soon.

[tolu-paystack]

Happy to submit the PR myself @just1and0. I can have one in later this afternoon

[just1and0]

Thanks for raising the issue and putting up a PR quickly 🔥 I will start working on the review.

[tolu-paystack]

No problem! Happy to contribute.

I also have some thoughts around the defaultChannels param, but will start a separate convo for that.

[just1and0]

@all-contributors
please add @tolu-paystack for bug.

[allcontributors]

@just1and0

I've put up a pull request to add @tolu-paystack! 🎉