Scroll lock everything in the background when the pop up is open

[Star3Lord]

Whenever the element containing the datepicker is longer than the viewheight, while scrolling through the dates, the background element also scrolls. Please scroll lock everything in the background when the pop up is open.

Thanks for awesome svelte datepicker component though.

[sinnerJoe]

@Star3Lord I fixed it in my fork, if you're still interested.
https://www.npmjs.com/package/@sinnerjoe/svelte-touch-datepicker