deps: update googleapis/java-cloud-bom digest to 59c776b #6976

Job	Run time
build(21) except self-service clients	11m 13s
build (11)	12m 34s
build (17)	12m 12s
build(8) except for gapic-generator-java	4m 4s
build(8) for gapic-generator-java	9m 10s
compatibility	1m 18s
dependency_analyzer_unit_test	23s
gapic-generator-java-bom	1m 33s
lint	26s
showcase (11)	3m 57s
showcase-clirr	2m 44s
showcase (17)	3m 56s
showcase-native	8m 0s
unmanaged_dependency_check	3m 59s
	1h 15m 29s

Provide feedback