do not require tf 1.x

Author: fedorov

notebooks/IDC_segmentation_primer.ipynb

@@ -451,8 +451,6 @@
         "\n",
         "from medpy.filter.binary import largest_connected_component\n",
         "\n",
-        "# use the \"tensorflow_version\" magic to make sure TF 1.x is imported\n",
-        "%tensorflow_version 1.x\n",
         "import tensorflow as tf\n",
         "import keras\n",
         "\n",