Fix for 724 Shulker Box not removed in My Items class

[Nesseley]

Summary

• This is a…
  • [X] Bug fix
  • [ ] Feature addition
  • [ ] Documentation
  • [ ] Refactoring
  • [ ] Minor / simple change (like a typo)
  • [ ] Other
• Describe this change in 1-2 sentences: It will now check if the item contains SHULKER_BOX instead of ending with _SHULKER_BOX to include all the shulkerboxes.

Problem

• GitHub issue: https://github.com/garbagemule/MobArena/issues/724

Solution

Action