fix hb description

cntmanage/flightslot/models/hourbuildings.py

@@ -63,6 +63,9 @@ class HourBuilding(models.Model):
         blank=True
     )
 
+    def __str__(self):
+        return f"Hour Building: {self.aircraft}"
+
 class HourBuildingLeg(models.Model):
     id = models.BigAutoField(
         primary_key=True