change rollup-plugin-babel to @rollup/plugin-babel

[mehdiraized]

hi plz upgrade this package

[swyxio]

lol why

[Conduitry]

@rollup/plugin-babel is the new official one, androllup-plugin-babel is deprecated. When I quickly tried to upgrade a project to the new version (which is also a new major version with breaking changes), I ran into some Babel helper configuration issues and put it aside for the time being, but this should be revisited soon.

[richardeschloss]

Warning that shows when running the command on sapper home page
"npm WARN deprecated [email protected]: This package has been deprecated and is no longer maintained. Please use @rollup/plugin-babel."

Minor edit: the spelling of the issue's title..."rullup --> rollup"

[mehdiraized]

#221