Update gems

This MR contains the following updates:

Package	Type	Update	Change
bigdecimal	ironbank-rubygems	patch	3.0.0 -> 3.0.2
bundler	ironbank-rubygems	patch	2.2.15 -> 2.2.20
concurrent-ruby	ironbank-rubygems	patch	1.1.8 -> 1.1.9
elasticsearch	ironbank-rubygems	minor	7.12.0 -> 7.13.1
elasticsearch-api	ironbank-rubygems	minor	7.12.0 -> 7.13.1
elasticsearch-transport	ironbank-rubygems	minor	7.12.0 -> 7.13.1
elasticsearch-xpack	ironbank-rubygems	minor	7.12.0 -> 7.13.1
excon	ironbank-rubygems	minor	0.79.0 -> 0.82.0
faraday	ironbank-rubygems	minor	1.3.0 -> 1.4.2
ffi	ironbank-rubygems	patch	1.15.0 -> 1.15.1
fluent-plugin-elasticsearch	ironbank-rubygems	patch	5.0.2 -> 5.0.4
fluent-plugin-kubernetes_metadata_filter	ironbank-rubygems	patch	2.7.0 -> 2.7.1
fluent-plugin-prometheus	ironbank-rubygems	patch	2.0.0 -> 2.0.1
fluent-plugin-systemd	ironbank-rubygems	patch	1.0.2 -> 1.0.5
http-cookie	ironbank-rubygems	patch	1.0.3 -> 1.0.4
kubeclient	ironbank-rubygems	patch	4.9.1 -> 4.9.2
oj	ironbank-rubygems	patch	3.11.3 -> 3.11.5
serverengine	ironbank-rubygems	patch	2.2.3 -> 2.2.4

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This MR has been generated by Renovate Bot.