Use latest version of ruby-build by default

[exterm]

It seems suboptimal that we need a PR every time a new ruby version is released, when that kind of stuff is really all handled in ruby-build. Is there any reason we can't use the latest ruby-build release by default (and fetch it on demand)?

[exterm]

@Stratus3D what do you think?

[runephilosof-abtion]

This is especially problematic when there are security updates.
It adds another manuel step, postponing the easy install of the update.

Also, the nodejs plugin does not have this manual step, so it would streamline how asdf plugins work.

[exterm]

@joshukraine we're now seeing another security update delayed by the process of merging a PR into this project. Would you consider a solution for auto-updating ruby-build?

[joshukraine]

@joshukraine we're now seeing another security update delayed by the process of merging a PR into this project. Would you consider a solution for auto-updating ruby-build?

Sorry for the delayed response. I somehow missed this comment when it first came through. I've seen a couple of possible solutions here:

1. The auto update of the ruby-build as you suggest
2. Arguably more conservative, the idea of automating a PR every time a ruby-build update comes through, making it that much easier to merge.

I'm definitely open to option two, and quite possibly option one as well. At the end of the day, I'd need to hear from @Stratus3D before we merge anything. In the meantime, I'm keeping a close eye on all ruby-build updates and working hard to get them merged within 24 hours of release.

Thanks again for your work on this, and I will try to provide more updates just as soon as I can!