chore: bump validation dapr runtime to 1.15.0-rc.2 #1316

Job	Run time
setup	20s
validate-example (actor)	2m 9s
validate-example (configuration)	1m 18s
validate-example (conversation)	1m 28s
validate-example (crypto)	1m 8s
validate-example (dist-scheduler)	1m 11s
validate-example (grpc-service)	2m 18s
validate-example (hello-world)	47s
validate-example (pubsub)	1m 54s
validate-example (streamsub)	1m 9s
validate-example (service)	2m 2s
validate-example (socket)	52s
validate-example (workflow)	1m 28s
validate-example (workflow-parallel)	58s
	19m 2s

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