save temp.pdf under /.cache to solve permission issues

LangChain_QA_Panel_App.ipynb

@@ -156,11 +156,11 @@
     "    \n",
     "    # save pdf file to a temp file \n",
     "    if file_input.value is not None:\n",
-    "        file_input.save(\"temp.pdf\")\n",
+    "        file_input.save(\"/.cache/temp.pdf\")\n",
     "    \n",
     "        prompt_text = prompt.value\n",
     "        if prompt_text:\n",
-    "            result = qa(file=\"temp.pdf\", query=prompt_text, chain_type=select_chain_type.value, k=select_k.value)\n",
+    "            result = qa(file=\"/.cache/temp.pdf\", query=prompt_text, chain_type=select_chain_type.value, k=select_k.value)\n",
     "            convos.extend([\n",
     "                pn.Row(\n",
     "                    pn.panel(\"\\U0001F60A\", width=10),\n",