add a newline at the end of regex.rs

src/util/regex.rs

@@ -1,4 +1,4 @@
 use once_cell::sync::Lazy;
 use regex::Regex;
 
-pub static RE_USERNAME: Lazy<Regex> = Lazy::new(|| Regex::new(r"^[a-zA-Z0-9_.]+$").unwrap());
+pub static RE_USERNAME: Lazy<Regex> = Lazy::new(|| Regex::new(r"^[a-zA-Z0-9_.]+$").unwrap());