D7309: vagrant: update vagrant image to buster from jessie

[durin42 (Augie Fackler)]

durin42 added a comment.


  I believe this was around to let people run tests in a friendly Linux environment more easily? We could probably burn it now that all of {Windows,MacOS,Linux} have good docker support..

REPOSITORY
  rHG Mercurial

BRANCH
  default

CHANGES SINCE LAST ACTION
  https://phab.mercurial-scm.org/D7309/new/

REVISION DETAIL
  https://phab.mercurial-scm.org/D7309

To: durin42, #hg-reviewers, indygreg
Cc: indygreg, mercurial-devel