Fixes a clippy warning:
```
warning: single-character string constant used as pattern
--> src/utils.rs:11:46
|
11 | escaped = Cow::Owned(escaped.replace("\"", "\\\""));
| ^^^^ help: try using a `char` instead: `'\"'`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#single_char_pattern
```
Dirkjan Ochtman
Zeeshan Ali
Damian Poddebniak