Added a few features requested by jokbon:

• An announcement system, which will periodically send a customizable message in the chat
• PlacheolderAPI support:
  4 placeholders:
  - lb_bounty => shows the number of bounties on a player
  - lb_collected => the number of bounties a player has collected
  - lb_top_bounty => the player with the most bounties
  - lb_top_col => the player who collected the most bounties

On top of the new features, I updated the spigot integration, so now the plugin should be completly compatible with 1.19

In the future I will add another placholder for the amount of items set on a player and/or the amount of money set on them