Mautrix

* Added support for message send checkpoints (as HTTP requests, similar to the
bridge state reporting system) by [sumnerevans].
* Added support for aiosqlite with the same interface as asyncpg.
* This includes some minor breaking changes to the asyncpg interface.
* Made config writing atomic (using a tempfile) to prevent the config
disappearing when disk is full.
* Changed prometheus to start before rest of `startup_actions`
(thanks to [Half-Shot] in [63]).
* Stopped reporting `STARTING` bridge state on startup by [sumnerevans].

[Half-Shot]: https://github.com/Half-Shot
[63]: https://github.com/mautrix/python/pull/63

* Added support for custom bridge bot welcome messages
(thanks to [justinbot] in [58]).

[justinbot]: https://github.com/justinbot
[58]: https://github.com/mautrix/python/pull/58

* Added support for disabling bridge management commands based on custom rules
(thanks to [tadzik] in [56]).

[tadzik]: https://github.com/tadzik
[56]: https://github.com/mautrix/python/pull/56

* Changed `remove_room_alias` to ignore `M_NOT_FOUND` errors by default, to
preserve Synapse behavior on spec-compliant server implementations.
The `raise_404` argument can be set to `True` to not suppress the errors.
* Fixed bridge state pings returning `UNCONFIGURED` as a global state event.

* **Breaking change (serialization):** Removed `Generic[T]` backwards
compatibility from `SerializableAttrs` (announced in [v0.9.6](https://github.com/mautrix/python/releases/tag/v0.9.6)).
* Stopped using `self.log` in `Program` config load errors as the logger won't
be initialized yet.
* Added check to ensure reply fallback removal is only attempted once.
* Fixed `remove_event_handler` throwing a `KeyError` if no event handlers had
been registered for the specified event type.
* Fixed deserialization showing wrong key names on missing key errors.

* Removed Python 3.9+ features that were accidentally used in v0.10.6.