syn 0.10.0 has been yanked

https://github.com/DanielKeep/rust-custom-derive/blob/53b7b2e/tests/derive-name-proc/Cargo.toml#L13 specifies dep

```toml
syn = "0.10.0"
```

However on https://crates.io/crates/syn/versions that version has now been yanked.