PEP8 cleanup

Signed-off-by: Jason Myers <jason@jasonamyers.com>

tests/force_insert_update/models.py

@@ -9,16 +9,20 @@ class Counter(models.Model):
     name = models.CharField(max_length = 10)
     value = models.IntegerField()
 
+
 class InheritedCounter(Counter):
     tag = models.CharField(max_length=10)
 
+
 class ProxyCounter(Counter):
     class Meta:
         proxy = True
 
+
 class SubCounter(Counter):
     pass
 
+
 class WithCustomPK(models.Model):
     name = models.IntegerField(primary_key=True)
     value = models.IntegerField()