docs: update README with v8 release announcement #516

Job	Run time
list-packages	4s
tests (ubuntu-latest, 20, redis-smq-common)	3m 15s
tests (ubuntu-latest, 20, redis-smq)	11m 9s
tests (ubuntu-latest, 20, redis-smq-rest-api)	2m 14s
	16m 42s

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