Update dependency langfuse to v4

Author: renovate-rancher[bot]

pyproject.toml

@@ -14,7 +14,7 @@ dependencies = [
     "langchain-openai==1.1.14",
     "langchain-text-splitters==1.1.2",
     "langchain-community==0.4.2",
-    "langfuse==3.14.5",
+    "langfuse==4.8.1",
     "langgraph==1.1.9",
     "langgraph-checkpoint-postgres==3.0.4",
     "mcp==1.26.0",