Disable debug in geocoder script

Looks like it was added to help in initial development:
https://github.com/alphagov/imminence/commit/cb0580f816e7a0fbcd9052f9b8a01e423e0ffcd1

This, along with other things being fixed, is writing to ``STDOUT`` on every run and so is causing unwanted emails to be sent, which is making @samjsharpe sad.