Bump golang.org/x/text from 0.20.0 to 0.21.0 #1012

Job	Run time
unit and integration tests	5m 35s
Build Operator image	2m 36s
kubectl rabbitmq tests	3m 34s
Local system tests (min k8s) (rabbitmq:3.13.0-management)	10m 53s
Local system tests (stable k8s) (rabbitmq:3.11.0-management)	9m 12s
Local system tests (min k8s) (rabbitmq:management)	9m 16s
Test upgrade of the operator	0s
Local system tests (stable k8s) (rabbitmq:management)	8m 47s
Documented example tests	0s
Local system tests (stable k8s) (pivotalrabbitmq/rabbitmq:main)	7m 55s
Release to GitHub Releases	0s
	57m 48s

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