Bump govuk_app_config from 1.3.0 to 1.3.1
Bump govuk_app_config from 1.3.0 to 1.3.1

Bumps [govuk_app_config](https://github.com/alphagov/govuk_app_config) from 1.3.0 to 1.3.1.
- [Changelog](https://github.com/alphagov/govuk_app_config/blob/master/CHANGELOG.md)
- [Commits](https://github.com/alphagov/govuk_app_config/compare/v1.3.0...v1.3.1)
alphagov/signonotron2,alphagov/signonotron2,alphagov/signonotron2,alphagov/signonotron2