Update inference.ipynb and fix app.py not found error

There IS no app.py in the main folder, you're supposed to run it via acestep, so I added the lines to install it use it instead

inference.ipynb

@@ -123,7 +123,9 @@
         "\n",
         "\n",
         "print(\" * Running UI...\")\n",
-        "!python app.py --checkpoint_path ./checkpoints/ --port 7865 --device_id 0 --share true --bf16 {bf16}"
+        "\n",
+        "!pip install e .",
+        "!acestep --checkpoint_path ./checkpoints/ --port 7865 --device_id 0 --share true --bf16 {bf16}"
       ],
       "metadata": {
         "cellView": "form",