Update to latest metrics-lib.

CHANGELOG.md

@@ -3,6 +3,7 @@
  * Minor changes
    - Set `Access-Control-Allow-Origin *` response header for bad
      requests, too.
+   - Update to metrics-lib 2.9.1.
 
 
 # Changes in version 7.0-1.21.0 - 2019-10-18

build.xml

@@ -12,7 +12,7 @@
   <property name="onionoo.protocol.version" value="7.0"/>
   <property name="release.version"
             value="${onionoo.protocol.version}-1.21.0-dev"/>
-  <property name="metricslibversion" value="2.6.2"/>
+  <property name="metricslibversion" value="2.9.1"/>
   <property name="jetty.version" value="-9.2.21.v20170120" />
   <property name="warfile"
             value="onionoo-${release.version}.war"/>