tests/test-mq-qsave.t

attr: vendor 22.1.0

The previous version was 5 years old, and pytype 2022.06.30 started complaining
about various uses (e.g. seeing `mercurial.thirdparty.attr._make._CountingAttr`
instead of `bytearray`).  Hopefully this helps.  Additionally, this has official
python 3.11 support.

The `attrs` package is left out, because it is simply a bunch of *.pyi stubs and
`from attr.X import *`, and that's not how they've been used up to this point.
We'd probably need to customize those anyway to
`from mercurial.thirdparty.attr import *`.

  $ echo "[extensions]" >> $HGRCPATH
  $ echo "mq=" >> $HGRCPATH

  $ hg init repo
  $ cd repo

  $ echo 'base' > base
  $ hg ci -Ambase
  adding base

  $ hg qnew -mmqbase mqbase

  $ hg qsave
  $ hg qrestore 2
  restoring status: hg patches saved state