[Test] Fix flaky optional combo test (#2755)

browser_tests/widget.spec.ts

@@ -47,6 +47,9 @@ test.describe('Combo text widget', () => {
     // Press R to trigger refresh
     await comfyPage.page.keyboard.press('r')
 
+    // Wait for nodes' widgets to be updated
+    await comfyPage.nextFrame()
+
     const refreshedComboValues = await getComboValues()
     expect(refreshedComboValues).not.toEqual(initialComboValues)
   })