feat: read token from environment

src/main.rs

@@ -53,9 +53,13 @@ struct Config {
 static CONFIG: Lazy<Config> = Lazy::new(Config::from_args);
 
 static GITHUB_TOKEN: Lazy<OsString> = Lazy::new(|| {
+    use std::env;
     use std::io::{stdin, BufRead, BufReader};
     use std::os::unix::prelude::*;
 
+    match env::var_os("PR_TRACKER_GITHUB_TOKEN") {
+        Some(token) => token,
+        None => {
             let mut bytes = Vec::with_capacity(41);
             if let Err(e) = BufReader::new(stdin()).read_until(b'\n', &mut bytes) {
                 eprintln!("pr-tracker: read: {}", e);
@@ -65,6 +69,8 @@ static GITHUB_TOKEN: Lazy<OsString> = Lazy::new(|| {
                 bytes.pop();
             }
             OsString::from_vec(bytes)
+        }
+    }
 });
 
 #[derive(Debug, Default, Template)]