Remove generate_gdextension_api_version! macro

We will soon have a #[cfg] definition that already needs to maintain a manual list of all Godot versions.
This is just another place to maintain, and basically acts as a test whether #[cfg(before_api/since_api)]
are working correctly. They currently do; if they don't, this will likely manifest differently anyway.

Author: Bromeon

godot-core/src/lib.rs

@@ -34,47 +34,6 @@ mod gen {
     include!(concat!(env!("OUT_DIR"), "/mod.rs"));
 }
 
-// ----------------------------------------------------------------------------------------------------------------------------------------------
-// API version check
-
-macro_rules! generate_gdextension_api_version {
-    (
-        $(
-            ($name:ident, $gdextension_api:ident) => {
-                $($version:literal, )*
-            }
-        ),* $(,)?
-    ) => {
-        $(
-            $(
-                #[cfg($gdextension_api = $version)]
-                #[allow(dead_code)]
-                const $name: &str = $version;
-            )*
-        )*
-    };
-}
-
-// If multiple gdextension_api_version's are found then this will generate several structs with the same
-// name, causing a compile error.
-//
-// This includes all versions we're developing for, including unreleased future versions.
-generate_gdextension_api_version!(
-    (GDEXTENSION_EXACT_API, gdextension_exact_api) => {
-        "4.0",
-        "4.0.1",
-        "4.0.2",
-        "4.0.3",
-        "4.0.4",
-        "4.1",
-        "4.1.1",
-    },
-    (GDEXTENSION_API, gdextension_minor_api) => {
-        "4.0",
-        "4.1",
-    },
-);
-
 // ----------------------------------------------------------------------------------------------------------------------------------------------
 // Hidden but accessible symbols