Update Readme with new Tag v0.15.0 #3895

Job	Run time
integration (v1.29.12, v0.59.5)	30m 27s
test-docker-build (base)	38s
e2e (v1.29.12, v0.59.5)	16m 2s
integration (v1.29.12, v0.68.0)	30m 41s
test-docker-build (git)	1m 7s
integration (v1.32.0, v0.59.5)	30m 6s
e2e (v1.29.12, v0.68.0)	24m 40s
integration (v1.32.0, v0.68.0)	29m 58s
test-docker-build (image-processing)	52s
e2e (v1.32.0, v0.59.5)	14m 5s
test-docker-build (waiter)	37s
e2e (v1.32.0, v0.68.0)	24m 17s
unit	3m 35s
	3h 27m 5s

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