[proposed upgrades] find a way to flag and remind maintainers to take care of MR

When a MR for proposed upgrades (requirements.txt or package.json) has it's tests green it should be easy for maintainers to merge it. For red dependency upgrades that fail it could result in a "we'll handle that one later, we're focusing on features" and for theses red MRs to be forgotten or become stock.

Maybe we could have a different reminder message, for example "make sure you have an issue created explaining why this MR is not managed (for now). And that this issue is visible to the team and maybe the client too".