Upgrade newrelic_rpm from 3.14.1.311 to 3.16.0.318.
What does this MR do?
While we intend to remove newrelic in the future, it'll probably not happen until 9.0 due to. In the meantime, I'd like to update the gem so it won't block Rails 5.
Changelog: https://github.com/newrelic/rpm/blob/master/CHANGELOG
Why was this MR needed?
Rails 5 compatibility.
Relevant issues: #14286 (closed), #12860 (closed)
cc: @rspeicher @dblessing