[ANNOUNCE] dbus-broker v23

[David Rheinsberg]

Hi

We just released v23 of dbus-broker. This includes the implementation
of `UnixGroupIDs` as defined by a recent dbus-specification update, as
well as a handful of fixes all over the place. All users are
recommended to upgrade.

https://github.com/bus1/dbus-broker/releases/tag/v23

## CHANGES WITH 23:

* Expose supplementary groups as `UnixGroupIDs` as defined by the dbus
specification in 0.53.

* Fix an issue where the launcher incorrectly reported success even
though it could not parse the bus configuration.

* Fix an issue where the launcher was unnecessarily verbose about trying
to start masked units. It will now only log once per unit.

* Fix an issue where transient systemd unit names were not correctly
escaped.

* The broker now uses the peer-pid from `SO_PEERCRED` on the controller
socket, rather than relying on `getppid()`. This allows creating the
broker from intermediate processes without having any credentials of
the intermediate leak into the broker.

Contributions from: David Rheinsberg

- Tübingen, 2020-05-11