Add limit to minimum window size (#13126)

Release Notes:

- Add a limit to the minimum window size on macOS.

Here's the minimum window before change:
<img width="121" alt="image"
src="https://github.com/zed-industries/zed/assets/38318044/9e907194-42e5-457e-91ea-96613426b479">

After change:
<img width="410" alt="image"
src="https://github.com/zed-industries/zed/assets/38318044/6e9c3057-9860-4f4b-9a73-c158ebac5ba9">

crates/collab_ui/src/collab_ui.rs

@@ -124,5 +124,6 @@ fn notification_window_options(
         display_id: Some(screen.id()),
         window_background: WindowBackgroundAppearance::default(),
         app_id: Some(app_id.to_owned()),
+        window_min_size: Size::default(),
     }
 }