docs: Fix doc issue for HANA Cloud Vector Engine (#22260)

- **Description:**
This PR fixes a rendering issue in the docs (Python notebook) of HANA
Cloud Vector Engine.

  - **Issue:** N/A
  - **Dependencies:** no new dependencies added

File of the fixed notebook:
`docs/docs/integrations/vectorstores/hanavector.ipynb`

docs/docs/integrations/vectorstores/sap_hanavector.ipynb

@@ -584,9 +584,9 @@
     "You are an expert in state of the union topics. You are provided multiple context items that are related to the prompt you have to answer.\n",
     "Use the following pieces of context to answer the question at the end.\n",
     "\n",
-    "```\n",
+    "'''\n",
     "{context}\n",
-    "```\n",
+    "'''\n",
     "\n",
     "Question: {question}\n",
     "\"\"\"\n",