Add tests in CI

Author: cbornet

.github/actions/setup-uv/action.yml

@@ -10,5 +10,5 @@ runs:
     - name: "Set up Python"
       uses: actions/setup-python@v5
       with:
-        python-version-file: "pyproject.toml"
+        python-version-file: "langchain/pyproject.toml"