Bump govuk_app_config from 9.23.7 to 9.23.8 #1384

Job	Run time
Test Ruby	31s
Security Analysis / Run Brakeman	30s
Run Pact tests / Verify pact tests	42s
Dependency Review scan / dependency-review-pr	11s
Lint Ruby / Run RuboCop	18s
CodeQL SAST scan / Analyze	1m 16s
Dependency Review scan / dependency-review-push	0s
	3m 28s

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