PreProcessor for AmplitudeModel #426

Job	Run time
conda install (ubuntu-20.04)	4m 40s
Build documentation	2m 17s
Unit tests (ubuntu-20.04, 3.7)	18m 24s
conda install latest tensorflow (ubuntu-20.04)	15m 51s
Unit tests (macos-11, 3.7)	22m 48s
Unit tests (ubuntu-20.04, 3.6)	21m 35s
Unit tests (ubuntu-20.04, 3.8)	13m 44s
Test uproot3 (ubuntu-20.04, 3.7)	22m 20s
Style checks	3m 16s
Coverage (ubuntu-20.04, 3.7)	19s
	2h 5m 14s

Provide feedback