Require secondary approval for fast-track

[avivkeller]

Currently, our fast-track rules require one non-author approval to land a PR.

I propose that we change this to either:

• One non-author, non-fast-track-requester approval
• Two non-author approvals

[MattIPv4]

One non-author, non-fast-track-requester approval

I'd be in favor of this. So, the author can request fast-track with an additional +1, but if someone else requests fast-track, then they also need an additional +1 (that isn't the author).