[2.9.6] Support for 1.21.8

Changes in Version 2.9.6

New features / Improvements:

• Added support for Minecraft 1.21.8 (v1_21_R5).
• Fixed skull texture fetching by replacing the discontinued Minetools API with a new system.
• Fixed placeholder expansion exceptions not being correctly caught and handled.
• Updated item-nbt-api to 2.15.2-SNAPSHOT.

API Changes:

• Added the following events: HologramRegisterEvent, HologramUnregisterEvent, HologramEnableEvent and HologramDisableEvent. (Thanks Andre601)

Have you found any bugs or mistakes? Please, report them on our Discord server.