[Chore] Update build-push-action to latest v6 #210

Job	Run time
nethermind (linux/amd64)	2m 40s
reth (linux/amd64, jemalloc,asm-keccak,optimism)	20m 46s
geth (linux/amd64)	3m 20s
geth (linux/arm64)	4m 41s
	31m 27s

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