Mautrix

* *(bridge)* Updated e2be helper to stop bridge if syncing fails.
* *(util.async_db)* Updated asyncpg connector to stop program if an asyncpg
`InternalClientError` is thrown. These errors usually cause everything to
get stuck.
* The behavior can be disabled by passing `meow_exit_on_ice` = `false` in
the `db_args`.

* *(util.formatter)* Added support for parsing `img` tags
* By default, the `alt` or `title` attribute will be used as plaintext.
* *(types)* Added `notifications` object to power level content class.
* *(bridge)* Added utility methods for handling incoming knocks in
`MatrixHandler` (thanks to [maltee1] in [103]).
* *(appservice)* Updated `IntentAPI` to add the `fi.mau.double_puppet_source`
to all state events sent with double puppeted intents (previously it was only
added to non-state events).

[103]: https://github.com/mautrix/python/pull/103

* *(bridge)* Fixed double puppeting `start` method not handling some errors
from /whoami correctly.
* *(types)* Added `com.beeper.message_send_status` event type for bridging
status.

* *(bridge.commands)* Added `reason` field for `CommandEvent.redact`.
* *(client.api)* Added `reason` field for the `unban_user` method
(thanks to [maltee1] in [101]).
* *(bridge)* Changed automatic DM portal creation to only apply when the invite
event specifies `"is_direct": true` (thanks to [maltee1] in [102]).
* *(util.program)* Changed `Program` to use create and set an event loop
explicitly instead of using `get_event_loop`.
* *(util.program)* Added optional `exit_code` parameter to `manual_stop`.
* *(util.manhole)* Removed usage of loop parameters to fix Python 3.10
compatibility.
* *(appservice.api)* Switched `IntentAPI.batch_send` method to use custom Event
classes instead of the default ones (since some normal event fields aren't
applicable when batch sending).

[maltee1]: https://github.com/maltee1
[101]: https://github.com/mautrix/python/pull/101
[102]: https://github.com/mautrix/python/pull/102

* *(types, bridge)* Dropped support for appservice login with unstable prefix.
* *(util.async_db)* Fixed some database start errors causing unnecessary noise
in logs.
* *(bridge.commands)* Added helper method to redact bridge commands.

* *(types)* Changed `set_thread_parent` to have an explicit option for
disabling the thread-as-reply fallback.