Upgrade mockito to 2.23.0
Upgrade mockito to 2.23.0

Change-Id: Iaa2731213f2ae2beb046d3ef39cabfe68d17527b
Signed-off-by: David Pursehouse <e7b5c6a4a3dbaca972851f8c075e19915752593f@collab.net>

dropwizard/metrics,dropwizard/metrics,dropwizard/metrics