Unexpected result using Latin1 encoding

Given the input:

```xml
<?xml version="1.0" encoding="ISO-8859-1"?>
<Envelope>
  <Body>
    Olá mundo
  </Body>
</Envelope>
```

`xml-rs` return `Body` value under `xml::reader::XmlEvent::Characters` to be `OlÃ¡ mundo`, which seems to be incorrect as `á` is valid character under ISO-8859-1 (Latin1) encoding.