[doc] add tqdm for link prediction tutorial (#6802)

notebooks/stochastic_training/link_prediction.ipynb

@@ -145,7 +145,7 @@
         "datapipe = datapipe.transform(partial(gb.exclude_seed_edges, include_reverse_edges=True))\n",
         "datapipe = datapipe.fetch_feature(feature, node_feature_keys=[\"feat\"])\n",
         "datapipe = datapipe.copy_to(device)\n",
-        "train_dataloader = gb.DataLoader(datapipe, num_workers=0)"
+        "train_dataloader = gb.DataLoader(datapipe)"
       ],
       "metadata": {
         "id": "LZgXGfBvYijJ"
@@ -315,7 +315,7 @@
         "\n",
         "logits = []\n",
         "labels = []\n",
-        "for step, data in enumerate(eval_dataloader):\n",
+        "for step, data in tqdm.tqdm(enumerate(eval_dataloader)):\n",
         "    # Get node pairs with labels for loss calculation.\n",
         "    compacted_pairs, label = data.node_pairs_with_labels\n",
         "\n",