pkgr.yml: update MPN date

[kyleam]

This brings over the @barrettk's initial commit from gh-610, which updates the MPN snapshot to one with nmrec. As discussed here, not doing so in gh-606 was an oversight, and it'd be good to get that into main without tying it up to an unrelated PR.

An additional reason for pulling it out is that it'll let us see whether Drone is still misbehaving: https://github.com/metrumresearchgroup/bbr/pull/606#issuecomment-1756226915

[barrettk]

Was just gona do this - thanks for taking care of it

[kyleam]

An additional reason for pulling it out is that it'll let us see whether Drone is still misbehaving

Hmm, no luck troubleshooting that. (Toggled off "require status check" for these with intent of toggling it right back on to see if the old off/on resolved it, but now the checks aren't event showing up as an option.)

Anyway, no reason to hold this up to debug more. We can open scratch PRs if needed.

[kyleam]

Here are the green drone runs:

• https://github-drone.metrumrg.com/metrumresearchgroup/bbr/3601
• https://github-drone.metrumrg.com/metrumresearchgroup/bbr/3608

Will merge (I can't officially approve this since I opened the PR).