dependencies.tsv: update github.com/juju/testing
dependencies.tsv: update github.com/juju/testing

Disabled mgo debugging/logging by default, which cuts out
a significant amount of mgo call overhead.

Hopefully fixes https://bugs.launchpad.net/juju/+bug/1625768

ericsnowcurrently/juju,mjs/juju,mikemccracken/juju,alesstimec/juju,mjs/juju,marcmolla/juju,anastasiamac/juju,bac/juju,mjs/juju,anastasiamac/juju,bac/juju,waigani/juju,alesstimec/juju,anastasiamac/juju,mjs/juju,marcmolla/juju,marcmolla/juju,waigani/juju,ericsnowcurrently/juju,mikemccracken/juju,alesstimec/juju,bac/juju,waigani/juju,bac/juju,waigani/juju,mjs/juju,alesstimec/juju,anastasiamac/juju,mjs/juju,marcmolla/juju,alesstimec/juju,ericsnowcurrently/juju,ericsnowcurrently/juju,mikemccracken/juju,anastasiamac/juju,mikemccracken/juju,marcmolla/juju,ericsnowcurrently/juju,mikemccracken/juju,bac/juju,mjs/juju