Auto DevOps herokuish is using ruby that conflicts with Gemfile

$ kc  logs production-db-initialize-nfgwr -n rails-staging-4339457
== Installing dependencies ==
Successfully installed bundler-2.0.1
Parsing documentation for bundler-2.0.1
Installing ri documentation for bundler-2.0.1
Done installing documentation for bundler after 5 seconds
1 gem installed
Your Ruby version is 2.3.1, but your Gemfile specified 2.5.1
Don't run Bundler as root. Bundler can ask for sudo if it is needed, and
installing your bundle as root will break this application for all non-root
users on this machine.
Your Ruby version is 2.3.1, but your Gemfile specified 2.5.1

== Command ["bundle install"] failed ==