Remove signing function - not required

Author: ovalle15

examples/annotation_import/image.ipynb

@@ -810,13 +810,6 @@
         "    ]\n",
         ")\n",
         "\n",
-        "# Create urls to mask data for upload\n",
-        "def signing_function(obj_bytes: bytes) -> str:\n",
-        "    url = client.upload_data(content=obj_bytes, sign=True)\n",
-        "    return url\n",
-        "\n",
-        "label.add_url_to_masks(signing_function)\n",
-        "\n",
         "# Convert our label from a Labelbox class object to the underlying NDJSON format required for upload \n",
         "label_ndjson = list(NDJsonConverter.serialize([label]))"
       ],