Update dependency @swc/core to ^1.4.2 #2266

Job	Run time
Dependencies, Unit tests (16)	1m 25s
Static analysis	1m 34s
Dependencies, Unit tests (18)	1m 28s
Dependencies, Unit tests (20)	1m 28s
Build libraries	1m 56s
Build application (govuk-docs)	2m 19s
Build application (govuk-template)	1m 33s
Test application (govuk-docs, chromium)	1m 37s
Test application (govuk-docs, firefox)	1m 25s
Test application (govuk-docs, electron)	1m 3s
Test application (govuk-template, chromium)	1m 58s
Test application (govuk-template, firefox)	1m 24s
Test application (govuk-template, electron)	1m 27s
	20m 37s

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