Features
1.21.3 support

Improvements
Fix players in vanish pickup up shot arrows
Fix not validating playername input in some commands
Add DiscordSRV advancement integration (see plugin staffplusplus cancel achievement on staffmode but discordsrv still sending them DiscordSRV/DiscordSRV#1766)
Fix some mobs still targeting vanished players (mobs that already targeted the player)
Fix a few issues that affected player who did not have invincibility in staff mode/vanish (as set in config)