Custom Login Messages

• make mod compatible with Minecraft 26.1

Make mod compatible with Minecraft 1.21.11:

• replaced deleted CommandSourceStack.hasPermission(...) by commandSourceStack.permissions().hasPermission(new Permission.HasCommandLevel(PermissionLevel.ADMINS))
• updated various dependencies

The mod's base has switched from Forge to NeoForge.

Upgrade mod to Minecraft 1.21

• The mod supports easier text formatting now. For example, use <> instead of §c to get red text (you cannot insert the § symbol in the chat window).