Fix the tagged version
Fix the tagged version

This hasn't been spotted upon review and resulted in stalling the
concourse pipeline in staging. The GitHub repo, has the tags prefixed
with a letter `v`, which in upgrade from `v0.6.0` to `0.7.0` has been
omitted.

Adding it pack to merge in quickly.

alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf