docs: variable should be let as it is reassigned (supabase#19217)

Author: probablyVincentIp

apps/docs/pages/guides/getting-started/tutorials/with-sveltekit.mdx

@@ -163,7 +163,7 @@ Update your `src/routes/+layout.svelte`:
 
 export let data
 
-const { supabase, session } = data
+let { supabase, session } = data
 $: ({ supabase, session } = data)
 
 onMount(() => {
@@ -314,7 +314,7 @@ Create a new `src/routes/account/+page.svelte` file with the content below.
 export let data
 export let form
 
-const { session, supabase, profile } = data
+let { session, supabase, profile } = data
 $: ({ session, supabase, profile } = data)
 
 let profileForm: HTMLFormElement