boards/kakute-f7-mini-v3: remove specification build hook

boards/kakute-f7-mini-v3/build.rs

@@ -1,5 +1,4 @@
 fn main() {
-    kaptan_spec::validate_package();
     println!("cargo:rerun-if-changed=build.rs");
     println!("cargo:rerun-if-changed=memory.x");
     println!("cargo:rustc-link-arg=-Tlink.x");