Vouch request: bestrand

[bestrand]

What do you want to work on?

I want to fix #4259 by pinning libkrun to sha for 1.19.6 here and other relevant files

OpenShell/crates/openshell-driver-vm/runtime/pins.env

Line 33 in 360c5a0

LIBKRUN_REF="${LIBKRUN_REF:-728df8125077d0db44265f6e997c72b81b65c015}"

Why this change?

Reduce time for cold start for sandboxes running via "vm" driver

Checklist

• I wrote this request myself (not AI-generated)
• I have read CONTRIBUTING.md