[ci] enforce latest available gem version and use the specific bundler version specified in the lock file

[lacostej]

I extracted this old code from #20293. I used it to ensure a more consistent environment across builds.

Checklist

• I've run bundle exec rspec from the root directory to see all new and existing tests pass
• I've followed the fastlane code style and run bundle exec rubocop -a to ensure the code style is valid
• I see several green ci/circleci builds in the "All checks have passed" section of my PR (connect CircleCI to GitHub if not)
• I've read the Contribution Guidelines
• I've updated the documentation if necessary.
• I've added or updated relevant unit tests.

Motivation and Context

Well now I remember why I did put that in #20293, the appveyor environment fails because we have a too old bundler on appveyor. So we should really merge this before we merge #20293...

Description

Testing Steps

[rogerluan]

Left some questions 🙇

[rogerluan]

💪