Fluid simulation doesn't works.

[Ynverxe]

Apparently the fluid simulation depends on Instance#setBlock calling the BlockPlacementRule#blockPlace method to update the fluid flow. I don't know what update it was, but apparently in the recent versions of Minestom this doesn't happen. I don't know if it is a bug or planned behavior.

More info: Minestom/Minestom#2011

[KrystilizeNevaDies]

This does seem like a bug, I can take a deeper look into it once I get a chance.

I'm not sure what the best way to go about this is, I would prefer not to use placeBlock if we can avoid it.