Bump govuk_app_config from 9.0.3 to 9.0.4 #469

Job	Run time
Lint Ruby / Run RuboCop	23s
Lint JavaScript / Run Standardx	14s
Lint SCSS / Run Stylelint	11s
Security Analysis / Run Brakeman	20s
Test JavaScript / Run Jasmine	1m 22s
Test Ruby / Run RSpec	2m 54s
	5m 24s

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