CI: Don't commit lockfile when publishing #3138

Job	Run time
Static analysis	1m 17s
Dependencies, Unit tests (18)	1m 52s
Dependencies, Unit tests (20)	1m 53s
Dependencies, Unit tests (22)	1m 51s
Build libraries	2m 19s
Build application (govuk-docs)	2m 15s
Build application (govuk-template)	1m 46s
Build application (next-example)	1m 39s
Build application (remix-example)	1m 14s
Test application (govuk-docs, chromium)	1m 53s
Test application (govuk-docs, firefox)	1m 38s
Test application (govuk-docs, electron)	1m 13s
Test application (govuk-template, chromium)	2m 8s
Test application (govuk-template, firefox)	1m 55s
Test application (govuk-template, electron)	1m 59s
Test application (next-example, chromium)	1m 53s
Test application (next-example, firefox)	1m 35s
Test application (next-example, electron)	1m 14s
Test application (remix-example, chromium)	1m 45s
Test application (remix-example, firefox)	1m 42s
Test application (remix-example, electron)	1m 21s
	36m 22s

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