Update image generation message to handle singular and plural cases

app.py

@@ -230,7 +230,7 @@ def _fn_generate_images(
     height: Optional[int] = None,
     **_
 ):
-    _fn_send_accept(message_id, chat_id, f"✨ Generating {count} image(s)…")
+    _fn_send_accept(message_id, chat_id, f"✨ Generating {count if count != 1 else 'a'} image{'s' if count != 1 else ''}...")
     for i in range(1, count+1):
         try:
             img, path, ret_p, url = generate_image(