Mautrix

* *(client)* Fixed error inviting users with custom member event content if the
server had disabled fetching profiles.
* *(util.utf16_surrogate)* Added utilities for adding/removing unicode
surrogate pairs in strings.
* *(util.magic)* Added check to make sure the parameter to `mimetype()` is
either `bytes` or `str`.

* **Breaking change *(util.message_send_checkpoint)*** Changed order of `send`
parameters to match `BridgeState.send` (this is not used by most software,
which is why the breaking change is in a patch release).
* *(util.async_db)* Changed the default size of the aiosqlite thread pool to 1,
as it doesn't reliably work with higher values.
* *(util.async_db)* Added logging for database queries that take a long time
(>1 second).
* *(client)* Added logging for sync requests that take a long time
(>40 seconds, with the timeout being 30 seconds).
* *(util.variation_selector)* Fixed variation selectors being incorrectly added
even if the emoji had a skin tone selector.
* *(bridge)* Fixed the process getting stuck if a config error caused the
bridge to stop itself without stopping the SQLite thread.
* Added pre-commit hooks to run black, isort and some other checks.

* *(util.formatter)* Removed the default handler for room pill conversion.
* This means they'll be formatted as normal links unless the bridge or other
thing using the formatter overrides `room_pill_to_fstring`.
* *(types)* Fixed the `event_id` property of `MatrixURI`s throwing an error
(instead of returning `None`) when the parsed link didn't contain a second
part with an event ID.

* Bumped minimum yarl version to 1.5. v1.4 and below didn't allow `URL.build()`
with a scheme but no host, which is used in the `matrix:` URI generator that
was added in v0.14.3.
* *(appservice)* Removed support for adding a `group_id` to user namespaces in
registration files.
* *(types)* Updated `Serializable.parse_json` type hint to allow `bytes` in
addition to `str` (because `json.loads` allows both).
* *(bridge)* Added `retry_num` parameter to `User.send_remote_checkpoint`.

* *(types)* Added `MatrixURI` type to parse and build `matrix:` URIs and
`https://matrix.to` URLs.
* *(util.formatter)* `matrix:` URIs are now supported in incoming messages
(using the new parser mentioned above).
* *(util.variation_selector)* Switched to generating list of emoji using data
directly from the Unicode spec instead of emojibase.
* *(util.formatter)* Whitespace in non-`pre` elements is now compressed into
a single space. Newlines are also replaced with a space instead of removed
completely. Whitespace after a block element is removed completely.
* *(util.ffmpeg)* Added option to override output path, which allows outputting
to stdout (by specifying `-`).
* *(util.config)* Changed `ConfigUpdateHelper.copy` to ignore comments if the
entity being copied is a commentable yaml object (e.g. map or list).

* *(appservice)* Fixed `IntentAPI` throwing an error when `redact` was called
with a `reason`, but without `extra_content`.