Update Puma to v6.3.0

What does this MR do and why?

This is needed to support a new feature for encrypted SSL keys: https://github.com/puma/puma/pull/3133

Relates to omnibus-gitlab#7799 (closed)

Diff: https://my.diffend.io/gems/puma/6.2.2/6.3.0

How to set up and validate locally

1. Check out this branch.
2. gdk restart rails-web
3. Everything should continue to work.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.