Skip some tests if numpy is not installed.
Skip some tests if numpy is not installed.

open-research/sumatra,apdavison/sumatra,babsey/sumatra,apdavison/sumatra,apdavison/sumatra,apdavison/sumatra,open-research/sumatra,open-research/sumatra,maxalbert/sumatra,open-research/sumatra,maxalbert/sumatra,maxalbert/sumatra,babsey/sumatra,babsey/sumatra,maxalbert/sumatra,dpad/sumatra,apdavison/sumatra,open-research/sumatra,dpad/sumatra,babsey/sumatra,dpad/sumatra,dpad/sumatra,maxalbert/sumatra,babsey/sumatra,dpad/sumatra