Ubuntu 21.10 is no longer supported

The Ubuntu 21.10 ("Impish Indri") release is no longer supported as ofJuly 14; users who are on that version will want to look intoupgrading soon.

This is a follow-up to the End of Life warning sent earlier to confirmthat as of July 14, 2022, Ubuntu 21.10 is no longer supported. No morepackage updates will be accepted to 21.10, and it will be archived toold-releases.ubuntu.com in the coming weeks.