Fix Svelte 4 slot rendering issues (#1763)

* Moved svelte:component into key block

* Formatting

---------

Co-authored-by: Jonathan Reinink <jonathan@reinink.ca>

packages/svelte/src/Render.svelte

@@ -14,12 +14,23 @@
   export let component
   export let props = {}
   export let children = []
+
+  let prevComponent
+  let key
+  $: {
+    if (prevComponent !== component) {
+      key = Date.now()
+      prevComponent = component
+    }
+  }
 </script>
 
 {#if $store.component}
-  <svelte:component this={component} {...props}>
-    {#each children as child, index (component && component.length === index ? $store.key : null)}
-      <svelte:self {...child} />
-    {/each}
-  </svelte:component>
+  {#key key}
+    <svelte:component this={component} {...props}>
+      {#each children as child, index (component && component.length === index ? $store.key : null)}
+        <svelte:self {...child} />
+      {/each}
+    </svelte:component>
+  {/key}
 {/if}