Pin dynatrace-metric-utils-java to 1.5.x for 1.9.x branch

There are breaking changes in the more recent minor version.

Author: shakuzen

dependencies.gradle

@@ -2,7 +2,7 @@ def VERSIONS = [
         'ch.qos.logback:logback-classic:1.2.+',
         'colt:colt:1.2.0',
         'com.amazonaws:aws-java-sdk-cloudwatch:latest.release',
-        'com.dynatrace.metric.util:dynatrace-metric-utils-java:latest.release',
+        'com.dynatrace.metric.util:dynatrace-metric-utils-java:1.5.+',
         'com.fasterxml.jackson.core:jackson-databind:latest.release',
         'com.github.ben-manes.caffeine:caffeine:2.+',
         'com.github.charithe:kafka-junit:latest.release',