Remove unneeded return statement

Clippy emits:

  warning: unneeded `return` statement

As suggested, remove the unneeded return statement.

src/util/key.rs

@@ -228,7 +228,7 @@ impl FromStr for PublicKey {
         match s.len() {
             66 => PublicKey::from_slice(&<[u8; 33]>::from_hex(s)?),
             130 => PublicKey::from_slice(&<[u8; 65]>::from_hex(s)?),
-            len => return Err(Error::Hex(hex::Error::InvalidLength(66, len)))
+            len => Err(Error::Hex(hex::Error::InvalidLength(66, len))),
         }
     }
 }

src/util/schnorr.rs

@@ -229,7 +229,7 @@ impl SchnorrSig {
                 // default type
                 let sig = secp256k1::schnorr::Signature::from_slice(sl)
                     .map_err(SchnorrSigError::Secp256k1)?;
-                return Ok( SchnorrSig { sig, hash_ty : SchnorrSighashType::Default });
+                Ok(SchnorrSig { sig, hash_ty: SchnorrSighashType::Default })
             },
             65 => {
                 let (hash_ty, sig) = sl.split_last().expect("Slice len checked == 65");