remove variation coeffisiont sale unti - change structure

apps/product/models.py

@@ -232,12 +232,11 @@ class SaleUnit(BaseModel):
         related_name='sale_unit',
         null=True
     )
-    unit = models.CharField(max_length=250, null=True)
-    variation_coefficient = models.IntegerField(default=0)
+    unit = models.CharField(max_length=250, null=True, unique=True)
     required = models.BooleanField(default=False)
 
     def __str__(self):
-        return f'{self.product.name} - {self.unit} - {self.variation_coefficient}'
+        return f'{self.product.name} - {self.unit}'
 
     def save(self, *args, **kwargs):
         return super(SaleUnit, self).save(*args, **kwargs)