Fix unused warning for `#[cfg_attr(test, macro_use)]` in `spongos/src/lib.rs`
#![no_std]
// Spongos requires heap allocation for Vectors and Strings
-#[cfg_attr(test, macro_use)]
+#[cfg_attr(all(test, not(feature = "std")), macro_use)]
extern crate alloc;
// Spongos requires the feature "std" for the Dump DDML command
