Puppet-ODL jobs failing to install bundler, RubyGems too old

The puppet-opendaylight jobs are failing with:

+ gem install bundler
ERROR: Error installing bundler: bundler requires RubyGems version >= 3.0.0. Try 'gem update --system' to update RubyGems itself.

Seems like the OS version of RubyGems is too old for the version of Bundler we have. I see in logs that OS is in-fact installing 2.0.14.1-34.el7_6.

https://logs.opendaylight.org/releng/vex-yul-odl-jenkins-1/packaging-puppet-test-sanity-master/18/console.log.gz