docs: update deprecated doc for solar.ipynb (#31337)

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docs/docs/integrations/chat/solar.ipynb

@@ -1,5 +1,13 @@
 {
  "cells": [
+  {
+   "cell_type": "markdown",
+   "id": "516cad96-cfcb-4dd1-b70e-ecaef33e60ba",
+   "metadata": {},
+   "source": [
+    "Deprecated since version 0.0.34: Use langchain_upstage.ChatUpstage instead."
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": 5,
@@ -72,7 +80,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.9.0"
+   "version": "3.12.10"
   }
  },
  "nbformat": 4,