Update to latest `godot-cpp` release

[limbonaut]

Update godot-cpp submodule to the latest version. It provides us with C++ bindings to Godot's GDExtesnion API.

Currently, we are pinning this dependency to a chosen release tag. Starting with version 10.x, godot-cpp is versioned independently from Godot Engine. This is what we need to do:

• Update our submodule to latest release,
• Add automatic dependency tracking
• Pass api_version=4.5 option to the build system - our minimum compatibility target

Related:

• Use single godot-cpp branch for Godot 4.1+ and version it independently from Godot godotengine/godot-proposals#10243

[linear]

GODOT-152