core release v0.18.0 (#3071)
core release v0.18.0 (#3071)

* [Gradle Release Plugin] - pre tag commit:  'v0.18.0-core'.

* [Gradle Release Plugin] - new version commit:  'v0.18.1-SNAPSHOT-core'.

Co-authored-by: mpeddada1 <267ca4da361aed88909da8d90f155f9db7655955@users.noreply.github.com>
GoogleContainerTools/jib,GoogleContainerTools/jib,GoogleContainerTools/jib,GoogleContainerTools/jib