chore: bump minikube action to 2.15.0 #6298

Job	Run time
sample_operators_tests (sample-operators/tomcat-operator)	2m 56s
sample_operators_tests (sample-operators/mysql-schema)	2m 35s
sample_operators_tests (sample-operators/webpage)	3m 16s
sample_operators_tests (sample-operators/leader-election)	3m 12s
	11m 59s

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