[checklist] Handling of bugs discovered post D3/V3

### Description

When discussing #13913 in the Hardware WGs Meeting, @OTshimeon raised that we should consider the option of allowing an IP to remain in D3/V3/L2 even if a bug is discovered post signoff if there is agreement by partners that an acceptable workaround exists.

I think this makes sense but right now the development stages don't allow for this. See e.g. https://opentitan.org/book/doc/project_governance/development_stages.html#versioning:

> After sign-off, three events could cause a change:
> - Bug found -> revert design and verification stage until fixed
> - Small collection of new features -> minor version increase, reset stages
> - New features to motivate a big change -> RFC, reset stages

This list is anyway going to be reworked once https://github.com/lowRISC/opentitan/issues/15856 has been put in place.