Pin upper bound of ultralytics, due to vulnerability

* ultralytics/ultralytics#18027

Author: LinasKo

notebooks/how-to-detect-and-count-objects-in-polygon-zone.ipynb

@@ -197,7 +197,7 @@
         }
       ],
       "source": [
-        "!pip install ultralytics\n",
+        "!pip install \"ultralytics<=8.3.40\"\n",
         "\n",
         "from IPython import display\n",
         "display.clear_output()\n",