51.1
====

* Improve the reliability of our GPU-is-ready detection (corrected the code that
  checks for the boot_display sysfs attribute)
* Restricted which PAM stacks GDM will run, to defend against malicious greeters
* oo7 enablement for Arch Linux's PAM stacks
* Fixed bug where gnome-headless-session@<user>.service would stop working if
  the user logs out from within the headless session
* Changed behavior of RemoteDisplayFactory API to wait for the new headless
  display to have a `session-id` set before returning/exporting it. This is a
  backwards-compatible change that makes it easier to use this API
* Code cleanups
* Translation updates