Mautrix

* 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`.

* *(util.ffmpeg)* Added simple utility module that wraps ffmpeg and tempfiles to convert audio/video files to different formats, primarily intended for bridging. FFmpeg must be installed separately and be present in `$PATH`.

* **Breaking change *(mautrix.util.formatter)*** Made `MatrixParser` async and non-static
* Being async is necessary for bridges that need to make database calls to convert mentions (e.g. Telegram has username mentions, which can't be extracted from the Matrix user ID).
* Being non-static allows passing additional context into the formatter by extending the class and setting instance variables.
* *(util.formatter)* Added support for parsing [spoilers](https://spec.matrix.org/v1.1/client-server-api/#spoiler-messages).
* *(crypto.olm)* Added `describe` method for `OlmSession`s.
* *(crypto)* Fixed sorting Olm sessions (now sorted by last successful decrypt time instead of alphabetically by session ID).
* *(crypto.store.asyncpg)* Fixed caching Olm sessions so that using the same session twice wouldn't cause corruption.
* *(crypto.attachments)* Added support for decrypting files from non-spec-compliant clients (e.g. FluffyChat) that have a non-zero counter part in the AES initialization vector.
* *(util.async_db)* Added support for using Postgres positional param syntax in the async SQLite helper (by regex-replacing `$<number>` with `?<number>`).
* *(util.async_db)* Added wrapper methods for `executemany` in `Database` and aiosqlite `TxnConnection`.
* *(bridge)* Changed portal cleanup to leave and forget rooms using double puppeting instead of just kicking the user.

* Fixed type hints in the `mautrix.crypto.store` module.
* Added debug logs for detecting crypto sync handling slowness.