chore: upgrade js sdk version for coagent starter project (CopilotKit#1877)

Author: ranst91

examples/coagents-starter/agent-js/package.json

@@ -15,7 +15,7 @@
     "typescript": "^5.6.3"
   },
   "dependencies": {
-    "@copilotkit/sdk-js": "^1.5.13",
+    "@copilotkit/sdk-js": "^1.8.13",
     "@langchain/anthropic": "^0.3.8",
     "@langchain/core": "^0.3.18",
     "@langchain/google-genai": "^0.1.4",