Update `langgraph` dependency in `pyproject.toml` to remove version constraints for greater flexibility.

pyproject.toml

@@ -31,7 +31,7 @@ dependencies = [
     "langchain-tavily>=0.1.5,<0.2.0",
     "langchain-text-splitters>=0.3.0,<0.4.0",
     "langfuse==3.6.1",
-    "langgraph>=0.6.0,<1.0.0",
+    "langgraph",
     "langgraph-checkpoint-mongodb>=0.2.2",
     "langgraph-runtime-inmem>=0.20.0,<0.21.0",
     "langgraph-sdk",