Bump docker/metadata-action from 5.5.0 to 5.6.1 #256

Job	Run time
build (dogstatsd, dogstatsd)	3m 3s
build (mutatedbyadmissioncontroller, mutated)	17s
build (nginx, http-client)	3m 5s
build (nginx, nginx-server)	24s
build (prometheus, prometheus)	3m 58s
build (redis, redis-client)	3m 14s
build (tracegen, tracegen)	3m 52s
build (npm-tools, go-httpbin)	26s
build (npm-tools, npm-tools)	19s
build (cws, cws-centos7)	1m 18s
build (logger, logger)	4m 13s
build (jmxfetch, jmx-test-app)	41s
build (fips, fips-server)	2m 54s
build (otel, calendar-go)	22s
build (gpu, cuda-basic)	4m 53s
	32m 59s

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