Update tutorial cu116 -> cu118. (#5636)

notebooks/sparse/graph_diffusion.ipynb

@@ -33,21 +33,9 @@
       "cell_type": "code",
       "execution_count": null,
       "metadata": {
-        "id": "F6eQWmWn7lqh",
-        "colab": {
-          "base_uri": "https://localhost:8080/"
-        },
-        "outputId": "f132ff09-a3ad-48be-f3eb-ccb1dd04bdb2"
+        "id": "F6eQWmWn7lqh"
       },
-      "outputs": [
-        {
-          "output_type": "stream",
-          "name": "stdout",
-          "text": [
-            "DGL installed!\n"
-          ]
-        }
-      ],
+      "outputs": [],
       "source": [
         "# Install required packages.\n",
         "import os\n",
@@ -58,7 +46,7 @@
         "# Uncomment below to install required packages. If the CUDA version is not 11.6,\n",
         "# check the https://www.dgl.ai/pages/start.html to find the supported CUDA\n",
         "# version and corresponding command to install DGL.\n",
-        "#!pip install dgl -f https://data.dgl.ai/wheels/cu116/repo.html > /dev/null\n",
+        "#!pip install dgl -f https://data.dgl.ai/wheels/cu118/repo.html > /dev/null\n",
         "#!pip install --upgrade scipy networkx > /dev/null\n",
         "\n",
         "try:\n",