net-p2p/openethereum: Unbreak with Rust 1.53.0

error[E0061]: this function takes 1 argument but 2 arguments were supplied
   --> cargo-crates/logos-derive-0.7.7/src/lib.rs:55:20
    |
55  |             extras.insert(util::ident(&ext), |_| panic!("Only one #[extras] attribute can be declared."));
    |                    ^^^^^^ -----------------  ----------------------------------------------------------- supplied 2 arguments
    |                    |
    |                    expected 1 argument
    |

http://package23.nyi.freebsd.org/data/114i386-default-foo/2021-06-18_08h49m22s/logs/errors/openethereum-3.2.6.log

PR:		256653