Failure to parse "\{"

[pjhuxford]

Here is an example demonstrating the issue:

use nom_bibtex::Bibtex;

fn main() {
    let src =
        r#"@book {fake_book, title = {Escaping: all about the \{ character},}"#;
    match Bibtex::parse(src) {
        Ok(bib) => {
            let entry = &bib.bibliographies()[0];
            println!("{}", entry.tags().get("title").unwrap());
        },
        Err(_) => {
            println!("Failed to correctly parse \\{{");
        }
    };
}

Expected output: Escaping: all about the \{ character or Escaping: all about the { character.

Observed output: Failed to correctly parse \{.

[charlesvdv]

Thanks for reporting the issue! Unfortunately, I'm pretty busy at the moment but I'm happy to accept a PR to fix the issue.