Remove reference to `govuk_setenv`.
Remove reference to `govuk_setenv`.

This internal script shouldn't be required for development test runs.

Fixes #263.

keithiopia/smart-answers,lutgendorff/smart-answers,ministryofjustice/smart-answers,tadast/smart-answers,aledelcueto/smart-answers,stwalsh/smart-answers,ministryofjustice/smart-answers,stwalsh/smart-answers,stwalsh/smart-answers,askl56/smart-answers,aledelcueto/smart-answers,stwalsh/smart-answers,askl56/smart-answers,tadast/smart-answers,tadast/smart-answers,alphagov/smart-answers,askl56/smart-answers,alphagov/smart-answers,aledelcueto/smart-answers,lutgendorff/smart-answers,lutgendorff/smart-answers,ministryofjustice/smart-answers,alphagov/smart-answers,alphagov/smart-answers,askl56/smart-answers,aledelcueto/smart-answers,keithiopia/smart-answers,tadast/smart-answers,lutgendorff/smart-answers,keithiopia/smart-answers