### What it does
Checks for wildcard dependencies in the `Cargo.toml`.

### Why is this bad?
[As the edition guide says](https://rust-lang-nursery.github.io/edition-guide/rust-2018/cargo-and-crates-io/crates-io-disallows-wildcard-dependencies.html),
it is highly unlikely that you work with any possible version of your dependency,
and wildcard dependencies would cause unnecessary breakage in the ecosystem.

### Example
```
[dependencies]
regex = "*"
```