fix: import untrack directly from client in svelte/attachments (#15974)

Author: paoloricciuti

.changeset/short-ads-rhyme.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: import untrack directly from client in `svelte/attachments`

packages/svelte/src/attachments/index.js

@@ -2,7 +2,7 @@
 /** @import { Attachment } from './public' */
 import { noop, render_effect } from 'svelte/internal/client';
 import { ATTACHMENT_KEY } from '../constants.js';
-import { untrack } from 'svelte';
+import { untrack } from '../index-client.js';
 import { teardown } from '../internal/client/reactivity/effects.js';
 
 /**