There's a merged pull request on the void-packages repository

xbps-src: add flag to show verbose messages
https://github.com/void-linux/void-packages/pull/48637

Description:
having to define/type out `XBPS_UPDATE_CHECK_VERBOSE` every time you want more diagnostics for `update-check` is really annoying (i even made a [wrapper](https://github.com/classabbyamp/xX_tools_Xx/blob/tools/xupcheck) for it previously, heh)

currently, this only applies to `update-check`, but if someone wants to add something later that can have higher verbosity, this would enable that.

#### Testing the changes
- I tested the changes in this PR: **YES**