Mautrix

* Added option to retry all HTTP requests when encountering a HTTP network
error or gateway error response (502/503/504)
* Disabled by default, you need to set the `default_retry_count` field in
`HTTPAPI` (or `Client`), or the `default_http_retry_count` field in
`AppService` to enable.
* Can also be enabled with `HTTPAPI.request()`s `retry_count` parameter.
* The `mautrix.util.network_retry` module was removed as it became redundant.
* Fixed GET requests having a body ([44]).

[44]: https://github.com/mautrix/python/issues/44

* Made HTTP request user agents more configurable.
* Bridges will now include the name and version by default.
* Added some event types and classes for space events.
* Fixed local power level check failing for `m.room.member` events.

* Added warning log when giving up on decrypting message.
* Added mimetype magic utility that supports both file-magic and python-magic.
* Updated asmux DM endpoint (`net.maunium.asmux` -> `com.beeper.asmux`).
* Moved RowProxy and ResultProxy imports into type checking ([46]).
This should fix SQLAlchemy 1.4+, but SQLAlchemy databases will likely be
deprecated entirely in the future.

[46]: https://github.com/mautrix/python/issues/46

* Made the Bridge class automatically fetch media repo config at startup.
Bridges are recommended to check `bridge.media_config.upload_size` before
even downloading remote media.

* Fixed the high-level `Client` class to not try to update state if there' no
`state_store` set.

* Added option to override the asyncpg pool used in the async `Database` wrapper.