Update dependency fluentd to v1.19.1

Author: renovate[bot]

docker/estenrye/fluentd-cloudtrail/Gemfile

@@ -12,7 +12,7 @@ gem "async-http", "= 0.59.2"
 
 gem "ext_monitor", "= 0.1.2"
 
-gem "fluentd", "= 1.14.6"
+gem "fluentd", "= 1.19.1"
 
 gem "bigdecimal", "= 3.1.2"