tut 39 - try setting user agent to prevent wikipedia error (#455)

Author: anakin87

tutorials/39_Embedding_Metadata_for_Improved_Retrieval.ipynb

@@ -132,7 +132,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 17,
+   "execution_count": null,
    "metadata": {},
    "outputs": [
     {
@@ -170,6 +170,8 @@
     "from haystack import Document\n",
     "from haystack.document_stores.in_memory import InMemoryDocumentStore\n",
     "\n",
+    "wikipedia.set_user_agent(\"haystack-tutorials\")\n",
+    "\n",
     "some_bands = \"\"\"The Beatles,The Cure\"\"\".split(\",\")\n",
     "\n",
     "raw_docs = []\n",