build(deps): bump docker/build-push-action from 3 to 6 #314

Job	Run time
e2e-pr / operator tests (kata-qemu, az-ubuntu-2004)	39m 42s
e2e-pr / operator tests (kata-qemu, az-ubuntu-2204)	33m 30s
e2e-pr / operator tests (kata-qemu, ubuntu-20.04)	18m 32s
e2e-pr / operator tests (kata-qemu, ubuntu-22.04)	18m 16s
e2e-pr / operator tests (kata-qemu, s390x-large)	13m 9s
e2e-pr / operator tests (kata-qemu-tdx, tdx)	15m 1s
e2e-pr / operator tests (kata-qemu-sev, sev)	10m 26s
e2e-pr / operator tests (kata-qemu-snp, sev-snp)	20m 16s
	2h 48m 52s

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