Bump prometheus.client.version from 1.3.7 to 1.3.8

Bumps `prometheus.client.version` from 1.3.7 to 1.3.8.

Updates `io.prometheus:prometheus-metrics-core` from 1.3.7 to 1.3.8

Updates `io.prometheus:prometheus-metrics-exporter-pushgateway` from 1.3.7 to 1.3.8

---
updated-dependencies:
- dependency-name: io.prometheus:prometheus-metrics-core
  dependency-version: 1.3.8
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: io.prometheus:prometheus-metrics-exporter-pushgateway
  dependency-version: 1.3.8
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

external/storm-metrics-prometheus/pom.xml

@@ -30,7 +30,7 @@
     <name>storm-metrics-prometheus</name>
 
     <properties>
-        <prometheus.client.version>1.3.7</prometheus.client.version>
+        <prometheus.client.version>1.3.8</prometheus.client.version>
     </properties>
 
     <dependencies>