build(deps): update langgraph-checkpoint-postgres requirement

Updates the requirements on [langgraph-checkpoint-postgres](https://github.com/langchain-ai/langgraph) to permit the latest version.
- [Release notes](https://github.com/langchain-ai/langgraph/releases)
- [Commits](langchain-ai/langgraph@checkpoint==2.0.16...checkpoint==3.0.0)

---
updated-dependencies:
- dependency-name: langgraph-checkpoint-postgres
  dependency-version: 3.0.0
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

pyproject.toml

@@ -36,7 +36,7 @@ dependencies = [
     "langchain-xai>=0.2.1",
     "langgraph (>=0.6.1,<0.7.0)",
     "langgraph-checkpoint>=2.0.18",
-    "langgraph-checkpoint-postgres>=2.0.16,<2.0.23",
+    "langgraph-checkpoint-postgres>=2.0.16,<3.0.1",
     "langgraph-prebuilt (>=0.6.1,<0.7.0)",
     "langmem>=0.0.27",
     "mypy-boto3-s3 (>=1.37.24,<2.0.0)",