Changed Godot version to 4.3

[quellus]

This is a draft because it's not tested yet. I'd like to run an exported version for a bit to make sure functionality is working properly.

What changed:

• Changed Godot version in the project.godot file
• Changed mentions of Godot version to 4.3 in the wiki
• Changed mentions of Godot version to 4.3 in the README