Add pytest and codecov badges
[![The project has reached a stable, usable state and is being actively developed.](https://www.repostatus.org/badges/latest/active.svg)](https://www.repostatus.org/#active)
[![code style black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/psf/black)
[![DOI](https://zenodo.org/badge/DOI/10.5281/zenodo.4426097.svg)](https://doi.org/10.5281/zenodo.4426096)
+[![pytest](https://github.com/PowerGenome/PowerGenome/actions/workflows/pytest.yml/badge.svg)](https://github.com/PowerGenome/PowerGenome/actions/workflows/pytest.yml)
+[![codecov](https://codecov.io/gh/PowerGenome/PowerGenome/branch/master/graph/badge.svg?token=7KJYLE3jOW)](https://codecov.io/gh/PowerGenome/PowerGenome)
**Note:** The code and data for PowerGenome are under active development and some changes may break existing functions. Keep up to date with major code and data releases by joining [PowerGenome on groups.io](https://groups.io/g/powergenome).
