Fix comment reference for function hash (#2307)

Co-authored-by: Francisco Giordano <frangio.1@gmail.com>

contracts/token/ERC721/ERC721.sol

@@ -65,7 +65,7 @@ contract ERC721 is Context, ERC165, IERC721, IERC721Metadata, IERC721Enumerable
      *     bytes4(keccak256('safeTransferFrom(address,address,uint256,bytes)')) == 0xb88d4fde
      *
      *     => 0x70a08231 ^ 0x6352211e ^ 0x095ea7b3 ^ 0x081812fc ^
-     *        0xa22cb465 ^ 0xe985e9c ^ 0x23b872dd ^ 0x42842e0e ^ 0xb88d4fde == 0x80ac58cd
+     *        0xa22cb465 ^ 0xe985e9c5 ^ 0x23b872dd ^ 0x42842e0e ^ 0xb88d4fde == 0x80ac58cd
      */
     bytes4 private constant _INTERFACE_ID_ERC721 = 0x80ac58cd;