Bump govuk_app_config from 9.2.0 to 9.4.0 #398

Job	Run time
Lint Ruby / Run RuboCop	21s
Lint JavaScript / Run Standardx	15s
Lint SCSS / Run Stylelint	11s
Security Analysis / Run Brakeman	17s
Test JavaScript / Run Jasmine	1m 10s
Test Ruby / Run RSpec	1m 57s
	4m 11s

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