Resolve "funkwhale-worker.service error option --concurrency"

Closes #1160

See merge request funkwhale/funkwhale!1296

Initial tracemalloc middleware,

See merge request funkwhale/funkwhale!1293

Properly handle redundant MediaSession play/pause requests

See merge request funkwhale/funkwhale!1283

MediaSession pause requests may happen even when Funkwhale is already in a
paused state. Previously FW would flip between play/pause without
consideration for the current state instead of doing nothing when
the playback state matches the requested one.

Notably, this made Funkwhale resume audio playback when entering sleep mode
on my system.

Stop all other tracks when loading a new track

Closes #1213 and #1387

See merge request funkwhale/funkwhale!1291

Make scripts more portable

See merge request funkwhale/funkwhale!1285

Improve UI consistency in an artist's tracklist

See merge request funkwhale/funkwhale!1286

Fix postcss warnings about old gradient syntax and justify-content: start

See merge request funkwhale/funkwhale!1287

Update howler.js dependency

Closes #1324

See merge request funkwhale/funkwhale!1289

Resolve "Failing to refetch federated tracks"

Closes #1303

See merge request funkwhale/funkwhale!1288

Reset playback on queue end

Closes #1380

See merge request funkwhale/funkwhale!1290

Closes #1380.

change struct to reflect subsonic api specs

See merge request funkwhale/funkwhale!1282