fix test

Author: dummdidumm

packages/svelte/tests/runtime-runes/samples/await-non-promise/main.svelte

@@ -2,7 +2,7 @@
 	let count = $state();
 </script>
 
-<button onclick={() => count += 1}>increment</button>
+<button onclick={() => count = 1}>number</button>
 <button onclick={() => count = null}>nullify</button>
 
 <p>