support Svelte 4

[benmccann]

$ npm init
$ npm install @sveltejs/vite-plugin-svelte@latest
$ npm install --loglevel svelte
npm WARN ERESOLVE overriding peer dependency
npm WARN While resolving: [email protected]
npm WARN Found: [email protected]
npm WARN node_modules/svelte
npm WARN   svelte@"^4.0.0-next.0" from the root project
npm WARN   2 more (@sveltejs/vite-plugin-svelte, @sveltejs/vite-plugin-svelte-inspector)
npm WARN 
npm WARN Could not resolve dependency:
npm WARN peer svelte@">=3.19.0" from [email protected]
npm WARN node_modules/@sveltejs/vite-plugin-svelte/node_modules/svelte-hmr
npm WARN   svelte-hmr@"^0.15.1" from @sveltejs/[email protected]
npm WARN   node_modules/@sveltejs/vite-plugin-svelte
npm WARN 
npm WARN Conflicting peer dependency: [email protected]
npm WARN node_modules/svelte
npm WARN   peer svelte@">=3.19.0" from [email protected]
npm WARN   node_modules/@sveltejs/vite-plugin-svelte/node_modules/svelte-hmr
npm WARN     svelte-hmr@"^0.15.1" from @sveltejs/[email protected]
npm WARN     node_modules/@sveltejs/vite-plugin-svelte