fix(multi-select): close menu when blurring the last filterable option

src/Checkbox/Checkbox.svelte

@@ -79,6 +79,7 @@
       on:change="{() => {
         checked = !checked;
       }}"
+      on:blur
     />
     <label for="{id}" title="{title}" class:bx--checkbox-label="{true}">
       <span

src/MultiSelect/MultiSelect.svelte

@@ -453,6 +453,9 @@
               labelText="{itemToString(item)}"
               checked="{item.checked}"
               disabled="{disabled}"
+              on:blur="{() => {
+                if (i === filteredItems.length - 1) open = false;
+              }}"
             />
           </ListBoxMenuItem>
         {/each}