### What it does
Checks for expressions where a character literal is cast
to `u8` and suggests using a byte literal instead.

### Why is this bad?
In general, casting values to smaller types is
error-prone and should be avoided where possible. In the particular case of
converting a character literal to u8, it is easy to avoid by just using a
byte literal instead. As an added bonus, `b'a'` is even slightly shorter
than `'a' as u8`.

### Example
```
'x' as u8
```

A better version, using the byte literal:

```
b'x'
```