GDExtension: Fix -Wtype-limits warning in compatibility_maximum patch check

[akien-mga]

Fixes this GCC 13.2.1 warning:

In file included from core/extension/scu/scu_core_extension.gen.cpp:2:
./core/extension/gdextension.cpp: In static member function 'static Error GDExtensionResourceLoader::load_gdextension_resource(const String&, Ref<GDExtension>&)':
./core/extension/gdextension.cpp:933:52: error: comparison of unsigned expression in '>= 0' is always true [-Werror=type-limits]
  933 |                         compatible = VERSION_PATCH <= compatibility_maximum[2];

And cleanup some dead code in version.h, we now always define VERSION_PATCH.

@godotengine/gdextension After confirming this is correct, feel free to merge the PR yourselves, to fix the warning in the master branch for other users.

[akien-mga]

This change was wrong, I misunderstood it. This is not an #ifdef but an #if, so that's indeed the logic which was responsible for keeping our version as 4.3.dev. I'll bring it back.

[akien-mga]

Done with 0246230.