I tried to give you examples and possible libraries which might be helpful to conduct DinD and Instrumental variable approaches, the most common ones of Quasi-experiment. You will not find detailed theoretical explanation of these methods from following readme files and python files. Because, I am assuming that you have already know how to do it in other softwares such as STATA, EVIEWS, and SAS.
If u are interested in the methodology and learning about it, I would recommend you three books in reference as further reading.
[1] J. M. Wooldridge, Introductory econometrics: A modern approach, Cengage learning, 2018.
[2] S. Cunningham, Causal Inference, Yale University Press, 2021.
[3] Angrist, J. D., & Pischke, J. S. (2009). Mostly harmless econometrics: An empiricist's companion. Princeton university press.