lalonde example notebook fails automated tests due to R dependency

[emrekiciman]

The lalonde example notebook uses the R Matching library to load the lalonde dataset. That is the only functionality it is providing to the notebook.

I recommend we remove the R dependency and load the lalonde dataset through python alone.

notebook link: https://github.com/py-why/dowhy/blob/main/docs/source/example_notebooks/dowhy_lalonde_example.ipynb failed build: https://github.com/py-why/dowhy/actions/runs/3147834064/jobs/5117731254