Lavalink

Additions
- Allow specifying timeout for aiohttp.

Fixes
- Fixed missing imports.

Additions
- Implement TypedDict classes for raw REST responses (e.g. `RawRouteplanner`, `RawInfo` etc).
- Implement `__str__` for Enum and `LoadResultError` classes.

Fixes
- Ignore `CancelledError` in event hook dispatching tasks.
- Fixed typing for `Client.remove_event_hooks`.
- Fixed return type for `get_routeplanner_status`.

Changes
- Bump required Python version to >=3.8.
- Bump minimum required aiohttp version.

Fixes
- Fixed an issue where long-running event-handling methods triggered by websocket messages could block the websocket connection.

Fixes
- Fixed a regression in 5.7.0 where instanting an `AudioTrack` from another `AudioTrack` may fail when `requester` cannot be accessed via dot notation as `data` has been reassigned to a dict.

Additions
- Allow setting filter values at instantiation.

Fixes
- Copy `requester` field when instantiating an `AudioTrack` from another `AudioTrack`.