Fix user_id consistency in 01_working_memory notebook

Changed user_id from 'demo_user' to student_id to match the user_id
used when retrieving working memory.

Author: abrookins

python-recipes/context-engineering/notebooks/section-3-memory/01_working_memory_with_extraction_strategies.ipynb

@@ -218,7 +218,7 @@
         "# Create WorkingMemory object\n",
         "working_memory = WorkingMemory(\n",
         "    session_id=session_id,\n",
-        "    user_id=\"demo_user\",\n",
+        "    user_id=student_id,\n",
         "    messages=memory_messages,\n",
         "    memories=[],\n",
         "    data={}\n",
@@ -227,7 +227,7 @@
         "await memory_client.put_working_memory(\n",
         "    session_id=session_id,\n",
         "    memory=working_memory,\n",
-        "    user_id=\"demo_user\",\n",
+        "    user_id=student_id,\n",
         "    model_name=\"gpt-4o\"\n",
         ")\n",
         "\n",