Inline format arguments

This feature has been stable since Rust 1.58.0.

src/mimefactory.rs

@@ -716,7 +716,7 @@ impl<'a> MimeFactory<'a> {
             }
             let message = message.replace_header(Header::new(
                 "Content-Type".to_string(),
-                format!("{} protected-headers=\"v1\";", existing_ct),
+                format!("{existing_ct} protected-headers=\"v1\";"),
             ));
 
             // Set the appropriate Content-Type for the outer message
@@ -1234,7 +1234,7 @@ impl<'a> MimeFactory<'a> {
                 Some(path) => match build_selfavatar_file(context, &path).await {
                     Ok(avatar) => headers.hidden.push(Header::new(
                         "Chat-User-Avatar".into(),
-                        format!("base64:{}", avatar),
+                        format!("base64:{avatar}"),
                     )),
                     Err(err) => warn!(context, "mimefactory: cannot attach selfavatar: {}", err),
                 },
@@ -1470,7 +1470,7 @@ fn render_rfc724_mid(rfc724_mid: &str) -> String {
     if rfc724_mid.chars().next().unwrap_or_default() == '<' {
         rfc724_mid
     } else {
-        format!("<{}>", rfc724_mid)
+        format!("<{rfc724_mid}>")
     }
 }
 
@@ -1535,7 +1535,7 @@ mod tests {
             Address::new_mailbox_with_name(display_name.to_string(), addr.to_string())
         );
 
-        println!("{}", s);
+        println!("{s}");
 
         assert_eq!(s, "=?utf-8?q?=C3=A4_space?= <x@y.org>");
     }