Upgrade to TypeScript?

[bherila]

@alexplumb would you support us converting over to typescript? I am happy to do the work to make the switch!!

See also https://github.com/braxex/mui-phone-input-ssr/issues/10

Thanks, Ben

[alexplumb]

This is something I would absolutely support

[alexplumb]

Let me know if there's anything needed of me for this to happen. Thanks for all the hard work!

[barrymichaeldoyle]

I might consider making a PR to make this happen in a week or 2 if nobody else gets to it :)