add Py Versions to MNIST Examples (#127)

* update Python version in MNIST notebook

* Add Py version to TF MNIST

Author: piyushghai

training/distributed_training/pytorch/data_parallel/mnist/pytorch_smdataparallel_mnist_demo.ipynb

@@ -104,6 +104,7 @@
     "                        entry_point='train_pytorch_smdataparallel_mnist.py',\n",
     "                        role=role,\n",
     "                        framework_version='1.6.0',\n",
+    "                        py_version='py3',\n",
     "                        # For training with multinode distributed training, set this count. Example: 2\n",
     "                        instance_count=2,\n",
     "                        # For training with p3dn instance use - ml.p3dn.24xlarge\n",

training/distributed_training/tensorflow/data_parallel/mnist/tensorflow2_smdataparallel_mnist_demo.ipynb

@@ -94,6 +94,7 @@
     "                        source_dir='code',\n",
     "                        entry_point='train_tensorflow_smdataparallel_mnist.py',\n",
     "                        role=role,\n",
+    "                        py_version='py3',\n",
     "                        framework_version='2.3.1',\n",
     "                        # For training with multinode distributed training, set this count. Example: 2\n",
     "                        instance_count=2,\n",