Bump govuk_publishing_components from 35.21.0 to 35.21.4 #1055

Job	Run time
Lint Ruby / Run RuboCop	33s
Lint JavaScript / Run Standardx	12s
Security Analysis / Run Brakeman	24s
Lint SCSS / Run Stylelint	17s
Test JavaScript / Run Jasmine	1m 7s
Test Ruby / Run Minitest	5m 28s
	8m 1s

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