Implemented leaving a gamenight on the server/database side

gamenight-cli/src/domain/user.rs

@@ -1,7 +1,16 @@
+use std::fmt::Display;
+
 use uuid::Uuid;
 
 #[derive(Clone)]
 pub struct User {
     pub id: Uuid,
     pub username: String
+}
+
+impl Display for User {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", self.username)
+        
+    }
 }