aoqiz

Granger causality

1

**Update** - Add auto test to Granger Causality. The ground truth `p_value_matrix_truth` and `adj_matrix_truth` are computed from the current version [1ebf232](https://github.com/cmu-phil/causal-learn/commit/1ebf232f0244a60fa7908bdea2b1bdf451da4074) **Test plan** `python -m unittest tests/TestGranger.py # should pass`...