Bump docker/metadata-action from 5.5.0 to 5.6.0 #254

Job	Run time
build (dogstatsd, dogstatsd)	2m 54s
build (mutatedbyadmissioncontroller, mutated)	15s
build (nginx, http-client)	2m 42s
build (nginx, nginx-server)	30s
build (prometheus, prometheus)	4m 28s
build (redis, redis-client)	2m 52s
build (tracegen, tracegen)	4m 1s
build (npm-tools, go-httpbin)	22s
build (npm-tools, npm-tools)	42s
build (cws, cws-centos7)	1m 7s
build (logger, logger)	4m 15s
build (jmxfetch, jmx-test-app)	38s
build (fips, fips-server)	3m 11s
build (otel, calendar-go)	13s
build (gpu, cuda-basic)	1m 45s
	29m 55s

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