requirements.txt for dev and testing

[fullcontrol-xyz]

consider adding dev_requirements.txt to separate requirements required to run volco from those required to develop volco.

maybe also cicd_requirements.txt

[fullcontrol-xyz]

Also, some requirements are hard-coded in two files (requirements.txt and .pre-commit-config.yaml). Add notes inthe two files to ensure anyone changing one file knows to change the other. Initial simple version of this repo may not need pre-commits