Added spawner modifiers.
All information about modifiers can be found in the modifiers.yml file. You can create, modify and remove modifiers.
!!! Note, that modifiers are still not fully finished and are released as a preview, they may change!

Added support for version 1.21.8
Added option to ignore version warnings, this will allow to load the plugin even if the version is not yet fully supported, however this may cause issues if server API has changed.

Fixed trusted player ignoring when manipulating with a spawner.
Fixed price API.