Set propper gamemode abilities, resolves #367

[Commandcracker]

Description

Set propper gamemode abilities, resolves #367

Testing

Tired out with /kill, still able to flying

Checklist

Things need to be done before this Pull Request can be merged.

• Code is well-formatted and adheres to project style guidelines: cargo fmt
• Code does not produce any clippy warnings: cargo clippy
• All unit tests pass: cargo test
• I added new unit tests, so other people don't accidentally break my code by changing other parts of the codebase. How?

[Commandcracker]

See net.minecraft.world.GameMode#setAbilities

[Snowiiii]

Looks good. Forgot to set the abilities when changing gamemode.
Thanks @Commandcracker 👍