Update prometheusServerVersion to v1.6.1

Author: renovate[bot]

dependencyManagement/build.gradle.kts

@@ -15,7 +15,7 @@ val jmhVersion = "1.37"
 val mockitoVersion = "4.11.0"
 val slf4jVersion = "2.0.17"
 val opencensusVersion = "0.31.1"
-val prometheusServerVersion = "1.5.1"
+val prometheusServerVersion = "1.6.1"
 val armeriaVersion = "1.38.0"
 val junitVersion = "5.14.3"
 val okhttpVersion = "5.3.2"