Bump govuk_app_config from 9.0.4 to 9.1.0 #284

Job	Run time
Lint Ruby / Run RuboCop	28s
Lint SCSS / Run Stylelint	13s
Security Analysis / Run Brakeman	22s
Lint JavaScript / Run Standardx	19s
Test Ruby / Run RSpec	1m 21s
	2m 43s

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