Add display impl for TransportStatus

Signed-off-by: Lee Smet <lee.smet@hotmail.com>

src/models/message.rs

@@ -59,6 +59,18 @@ pub enum TransportStatus {
     Failed,
 }
 
+impl std::fmt::Display for TransportStatus {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            TransportStatus::Queued => f.write_str("queued"),
+            TransportStatus::Sent => f.write_str("sent"),
+            TransportStatus::Delivered => f.write_str("delivered"),
+            TransportStatus::Read => f.write_str("read"),
+            TransportStatus::Failed => f.write_str("failed"),
+        }
+    }
+}
+
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub enum MessageFormatType {
     Html,