[skip ci] Update MNIST_on_TPU.ipynb (#2252)

* Update MNIST_on_TPU.ipynb

* applied suggestions

Co-authored-by: vfdev <vfdev.5@gmail.com>

Author: FarehaNousheen

examples/notebooks/MNIST_on_TPU.ipynb

@@ -67,9 +67,9 @@
         "id": "4mnaxX3eXNGd"
       },
       "source": [
-        "VERSION = \"1.5\"\n",
-        "!curl https://raw.githubusercontent.com/pytorch/xla/master/contrib/scripts/env-setup.py -o pytorch-xla-env-setup.py\n",
-        "!python pytorch-xla-env-setup.py --version $VERSION"
+        "VERSION = !curl -s https://api.github.com/repos/pytorch/xla/releases/latest | grep -Po '\"tag_name\": \"v\\K.*?(?=\")'\n",
+        "VERSION = VERSION[0].rstrip('.0') # remove trailing zero\n",
+        "!pip install cloud-tpu-client==0.10 https://storage.googleapis.com/tpu-pytorch/wheels/torch_xla-{VERSION}-cp37-cp37m-linux_x86_64.whl"
       ],
       "execution_count": null,
       "outputs": []
@@ -345,7 +345,7 @@
         "    avg_accuracy = metrics[\"accuracy\"]\n",
         "    avg_nll = metrics[\"nll\"]\n",
         "    pbar.log_message(\n",
-        "        \"Training Results - Epoch: {engine.state.epoch}  Avg accuracy: {avg_accuracy:.2f} Avg loss: {avg_nll:.2f}\"\n",
+        "        f\"Training Results - Epoch: {engine.state.epoch}  Avg accuracy: {avg_accuracy:.2f} Avg loss: {avg_nll:.2f}\"\n",
         "    )\n",
         "    writer.add_scalar(\"training/avg_loss\", avg_nll, engine.state.epoch)\n",
         "    writer.add_scalar(\"training/avg_accuracy\", avg_accuracy, engine.state.epoch)\n",
@@ -358,7 +358,7 @@
         "    avg_accuracy = metrics[\"accuracy\"]\n",
         "    avg_nll = metrics[\"nll\"]\n",
         "    print(\n",
-        "        \"Validation Results - Epoch: {engine.state.epoch}  Avg accuracy: {avg_accuracy:.2f} Avg loss: {avg_nll:.2f}\"\n",
+        "        f\"Validation Results - Epoch: {engine.state.epoch}  Avg accuracy: {avg_accuracy:.2f} Avg loss: {avg_nll:.2f}\"\n",
         "    )\n",
         "    writer.add_scalar(\"valdation/avg_loss\", avg_nll, engine.state.epoch)\n",
         "    writer.add_scalar(\"valdation/avg_accuracy\", avg_accuracy, engine.state.epoch)"
@@ -395,4 +395,4 @@
       "outputs": []
     }
   ]
-}
+}