* Upgraded to support only Python 3.9+.
* Added Prometheus metrics support.
* Infrastructure: improved Docker container dependency management by moving more
  of the packages to use the Alpine-provided versions.
* On DM rooms, set the topic to the other users' occupation and include a link
  to to their LinkedIn profile. This option can be turned off by setting
  `bridge.set_topic_on_dms` to `false`.
* Added support for custom names on group chats and handling name change events.
* Added handling for emote formatting on plain-text messages.
* When a chat is read in Matrix, it is now marked as read in LinkedIn.
* Improved handling of promotional InMail messages.
* Bug fix: respect `bridge.initial_chat_sync` and `backfill` parameters.
* Send more bridging errors to the room.