Merge tag 'v1.12.4'

Synapse v1.12.4

Features:

* Always send users their own device updates. (#7160)
* Add support for handling GET requests for account_data on a worker. (#7311)

Bugfixes:

* Fix a bug that prevented cross-signing with users on worker-mode synapses. (#7255)
* Do not treat display names as globs in push rules. (#7271)
* Fix a bug with cross-signing devices belonging to remote users who did not share a
  room with any user on the local homeserver. (#7289)