Remove unneeded whitespace

We do not customarily put two lines of whitespace before modules.

Remove unneeded whitespace from before the `benches` module.

Author: tcharding

src/ecdsa/recovery.rs

@@ -452,7 +452,6 @@ mod tests {
     }
 }
 
-
 #[cfg(all(test, feature = "unstable"))]
 mod benches {
     use rand::{thread_rng, RngCore};