Update dependency org.mockito:mockito-core to v5.16.0

Author: renovate[bot]

gradle/libs.versions.toml

@@ -6,7 +6,7 @@ jetbrains-annotations = "26.0.2"
 jetty = "10.0.24" # version 11 breaks the Prometheus API
 junit-jupiter = "5.10.2"
 logback = "1.5.17"
-mockito = "5.15.2"
+mockito = "5.16.0"
 okhttp = "4.12.0"
 owner = "1.0.12"
 prometheus-simpleClient = "0.16.0"