Example in README doesn't compile

[danilaml]

There are errors about dyn Error and priority.

This one worked:

use std::error::Error;

use tokio;
use jira_query::JiraInstance;

#[tokio::main]
async fn main() -> Result<(), Box<dyn Error>> {
    let jira = JiraInstance::at("https://issues.redhat.com".to_string())?;

    let issue = jira.issue("CS-1113").await?;

    assert_eq!(issue.fields.priority.unwrap().name, "Normal");

    Ok(())
}