fluent-plugin-systemd out of date

Hi
I'm running a customized fluentd-gcp image (it just adds the fluent-plugin-rewrite-tag-filter plugin). I had to upgrade to the latest fluentd-gcp image recently because fluentd started crashing on gke with the version we were running. However I'm having trouble using the latest fluentd-gcp image (2.0.18). When I run fluentd with fluent-plugin-rewrite-tag-filter ~>2.1 installed, it fails on dependency conflict
```
Unable to activate fluent-plugin-systemd-0.0.11, because fluentd-1.2.5 conflicts with fluentd (~> 0.12) path=nil error_class=Gem::ConflictError error="Unable to activate fluent-plugin-systemd-0.0.11, because fluentd-1.2.5 conflicts with fluentd (~> 0.12)
```
I'm not sure how much testing is required to upgrade the fluent-plugin-systemd plugin to latest?