refactor(platform-server): replace ToString impl with Display for SubmissionStatus

Author: eureka0928

crates/platform-server/src/models/mod.rs

@@ -59,15 +59,16 @@ pub enum SubmissionStatus {
     Rejected,
 }
 
-impl ToString for SubmissionStatus {
-    fn to_string(&self) -> String {
-        match self {
-            SubmissionStatus::Pending => "pending".to_string(),
-            SubmissionStatus::Evaluating => "evaluating".to_string(),
-            SubmissionStatus::Completed => "completed".to_string(),
-            SubmissionStatus::Failed => "failed".to_string(),
-            SubmissionStatus::Rejected => "rejected".to_string(),
-        }
+impl std::fmt::Display for SubmissionStatus {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let s = match self {
+            SubmissionStatus::Pending => "pending",
+            SubmissionStatus::Evaluating => "evaluating",
+            SubmissionStatus::Completed => "completed",
+            SubmissionStatus::Failed => "failed",
+            SubmissionStatus::Rejected => "rejected",
+        };
+        write!(f, "{}", s)
     }
 }