Update to version 2.5.1 of the fluent-plugin-kubernetes_metadata_filter

Author: Ghazgkull

cluster/addons/fluentd-elasticsearch/fluentd-es-image/Gemfile

@@ -5,7 +5,7 @@ gem 'fluentd', '1.9.3'
 gem 'fluent-plugin-concat', '2.4.0'
 gem 'fluent-plugin-detect-exceptions', '0.0.13'
 gem 'fluent-plugin-elasticsearch', '4.0.9'
-gem 'fluent-plugin-kubernetes_metadata_filter', '2.4.6'
+gem 'fluent-plugin-kubernetes_metadata_filter', '2.5.1'
 gem 'fluent-plugin-multi-format-parser', '1.0.0'
 gem 'fluent-plugin-prometheus', '1.8.0'
 gem 'fluent-plugin-systemd', '1.0.2'