Fastlane Bundler 2 not available for macos machines

[Averylamp]

I have started with the default config.yml file, taken directly from the current Fastlane config, found here: https://circleci.com/docs/2.0/testing-ios/ .
Unfortunately macos machines do not have bundler upgraded to 2.0, which I would like to use.

#!/bin/bash --login -o pipefail
bundle install
^D��^D��You must use Bundler 2 or greater with this lockfile.
Exited with code 20

The build-and-test job fails on bundle install because of versioning, but I was unable to find any documentation or do anything that allowed me to upgrade bundler to version 2.

[Averylamp]

Update I got bundler 2 installed by using

- run: echo | sudo gem uninstall -I bundler
- run:
    name: Set Ruby Version
    command:  echo "ruby-2.4" > ~/.ruby-version
- run: sudo gem update --system
- run: sudo gem install --force bundler
- run: bundler --version
- run: bundle install