Redundant pip install invocations in jenkins tests?

[nbren12]

The requirements are installed here:
https://github.com/VulcanClimateModeling/fv3gfs-util/blob/c98b077c52759bee589f30062d62149098de3088/.jenkins/actions/test.sh#L71-L71

and here:
https://github.com/VulcanClimateModeling/fv3gfs-util/blob/d8b37264a26becf763fe7f5988a1190c54d2c9a7/.jenkins/jenkins.sh#L53-L56

It's not really clear what the resulting version of the requirements would be installed. Once #50 is merged, it might be cleaner to use tox for the jenkins builds as well.