Update to upstream version '4.28.1'
with Debian dir 3502f50686733fb6bbaf7f4a9e059c1872825ad2

Relax version constraints of net-s{sh,cp}

See merge request !1

net-ssh 6.x compatibility was added by upstream with no further changes
here:

https://github.com/puppetlabs/beaker/commit/582e72b

and net-scp 3.x compatibility does not introduce any test regression,
proposed to upstream here:

https://github.com/puppetlabs/beaker/pull/1661

Update to upstream version '4.21.0'
with Debian dir bb969a663fa734e71bb071c75f88e70c5d3833f0

(MAINT) add changelog for 4.1.0 release

[skip ci]

(PUP-9212) Allow for alpine platform

(PUP-9136) Preserve host hash from beaker exec run

(BKR-1432) Test if puppet module is directly in source host root

The alpine platform is common for docker containers; allowing for it
gives beaker-docker the context necessary to sideload ssh onto the
container.

(MAINT) handle commandfailures in rsync tests

In my previous work on this:
  https://github.com/puppetlabs/beaker/pull/1546
I took care of the cases where the method returned successfully
but the issue we are seeing in CI is where exceptions are
being thrown by the Host#do_rsync_to method. These changes take
the exceptions into account, allowing them to be other cases that
end similarly to the first, where we just continue backoff
execution

Prior to this change, we were losing state that had been set up when
running our pre-suite. Unfortunately, this oversight wasn't felt because
beaker was loading these defaults automatically for every beaker
invocation. In beaker 4, that functionality was removed, and we found
that state between beaker subcommand invocations was unfortunately not
preserved. This commit adds in an optional flag `--preserve-state` that
users can pass into a `beaker exec` invocation. This will update the
beaker options file to amend the host has to include any new or updated
information. This is particularly relevant for paths like
privatebindir` that are referenced in tests.

(MAINT) fix changelog entry

The changelog entry from this PR is old:
  https://github.com/puppetlabs/beaker/pull/1496
This change pulls the changelog entry from back
then into the now

[skip ci]

* (MAINT) Update RHEL support for GCE

Updated RHEL tests and support as discovered when testing the GCE
patches in beaker-google.

* re-add accidentally removed code

(MAINT) add rsync backoff for testing

Before, we would have a number of tests fail where
it was caused by some connection error that if we
had run it again, it probably would not be a problem.
This change allows these calls to be made with backoffs
so that the tests will be a little slower occasionally,
but much more resilient to network issues

Revert "(PUP-8305) Enable git-based acceptance testing"

This reverts commit 731661b5.