Chore(test): update rbenv

[roger-zhangg]

Which issue(s) does this change fix?

rbenv in appveyor doesn't support 3.4.7 yet

Why is this change necessary?

How does it address the issue?

What side effects does this change have?

Mandatory Checklist

PRs will only be reviewed after checklist is complete

• Review the generative AI contribution guidelines
• Add input/output type hints to new functions/methods
• Write design document if needed (Do I need to write a design document?)
• Write/update unit tests
• Write/update integration tests
• Write/update functional tests if needed
• make pr passes
• make update-reproducible-reqs if dependencies were changed
• Write documentation

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[valerena]

I guess we're migrating out of AppVeyor soon, but something that probably works for GitHub actions too: (not for now, but maybe if you see something like this in the future)

We should create more small scripts (under tests/ maybe) that do these kind of "multi-steps" actions, like install_ruby.sh that hides the complexity for the installation and we can just call from the big scripts. That way we need just one line of code for all the tests that run Ruby tests instead of having to put all the steps in all the places.