Simple fix to colab google#1020

Author: mingxingtan

efficientnetv2/tfhub.ipynb

@@ -36,7 +36,7 @@
         "    <img src=\"https://www.tensorflow.org/images/GitHub-Mark-32px.png\" />View source on github\n",
         "  </a>\n",
         "</td><td>\n",
-        "  <a target=\"_blank\"  href=\"https://colab.sandbox.google.com/github/google/automl/blob/master/efficientnetv2/tutorial.ipynb\">\n",
+        "  <a target=\"_blank\"  href=\"https://colab.sandbox.google.com/github/google/automl/blob/master/efficientnetv2/tfhub.ipynb\">\n",
         "    <img width=32px src=\"https://www.tensorflow.org/images/colab_logo_32px.png\" />Run in Google Colab</a>\n",
         "</td><td>\n",
         "    <!----<a href=\"https://tfhub.dev/google/collections/image/1\"><img src=\"https://www.tensorflow.org/images/hub_logo_32px.png\" />TF Hub models</a>--->\n",
@@ -649,4 +649,4 @@
       ]
     }
   ]
-}
+}