Bump govuk_app_config from 8.0.2 to 9.0.2 #258

Job	Run time
Lint SCSS / Run Stylelint	15s
Lint JavaScript / Run Standardx	12s
Lint Ruby / Run RuboCop	31s
Security Analysis / Run Brakeman	26s
Test JavaScript / Run Jasmine	1m 20s
Test Ruby / Run Minitest	8m 23s
	11m 7s

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