fix(aurora): remove empty lines in changes_factory and fix timestamp formatting

aurora/models/change.py

@@ -22,6 +22,12 @@ class Change(AuroraBaseModel):
     def unix_timestamp(self) -> int:
         return int(self.timestamp.timestamp())
 
+    @property
+    def unix_end_timestamp(self) -> Optional[int]:
+        if self.end_timestamp:
+            return int(self.end_timestamp.timestamp())
+        return None
+
     def __str__(self):
         return f"{self.type} {self.user_id} {self.reason}"