add dependancies to enable tests to run
there is a slight missmatch in html classes in `js.snap` test vectors
when tests are run with storybook is built using `storybook dev` vs
`storybook build`
start with a nix boilerplate for svelte that supports reproducible
builds
taken unedited from https://github.com/knarkzel/sveltekit-nix
c444859e97fb13393ad6e295132412bbea044e32
DanConwayDev
jk