Remove extra parenthesis (#1919)

Author: xotonic

contracts/cryptography/ECDSA.sol

@@ -22,7 +22,7 @@ library ECDSA {
      * IMPORTANT: `hash` _must_ be the result of a hash operation for the
      * verification to be secure: it is possible to craft signatures that
      * recover to arbitrary addresses for non-hashed data. A safe way to ensure
-     * this is by receiving a hash of the original message (which may otherwise)
+     * this is by receiving a hash of the original message (which may otherwise
      * be too long), and then calling {toEthSignedMessageHash} on it.
      */
     function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {