v30.3.0-rc.0

✨ Features

• Element-R: disable sending room key requests (#3939). Contributed by @richvdh.

🐛 Bug Fixes

• Fix notifications appearing for old events (#3946). Contributed by @dbkr.
• Don't back up keys that we got from backup (#3934). Contributed by @uhoreg.
• Fix upload with empty Content-Type (#3918). Contributed by @JakubOnderka.
• Prevent phantom notifications from events not in a room's timeline (#3942). Contributed by @dbkr.