fix: adjust snippet helper type to new snippet API

The `Snippet` type definition has changed. It's an array of arguments now, so we need to adjust our helper
#2293

Author: dummdidumm

packages/svelte2tsx/svelte-shims-v4.d.ts

@@ -148,8 +148,8 @@ declare function __sveltets_2_cssProp(prop: Record<string, any>): {};
 // @ts-ignore Svelte v3/v4 don't have this
 declare function __sveltets_2_ensureSnippet(val: ReturnType<import('svelte').Snippet>): any;
 // @ts-ignore Svelte v3/v4 don't have this
-declare function __sveltets_2_snippet(): import('svelte').Snippet<void>;
-declare function __sveltets_2_snippet<T>(t: T): import('svelte').Snippet<T>;
+declare function __sveltets_2_snippet(): import('svelte').Snippet;
+declare function __sveltets_2_snippet<T>(t: T): import('svelte').Snippet<[T]>;
 
 /** @internal PRIVATE API, DO NOT USE */
 type __sveltets_2_SvelteAnimationReturnType = {