Merge multiple isinstance() calls to one (#6513)

* Merge multiple isinstance() calls to one

See https://docs.python.org/3/library/functions.html#isinstance

* Fix `)` mismatch

Fix `)` mismatch

Author: PatrickCai

rest_framework/utils/field_mapping.py

@@ -106,8 +106,7 @@ def get_field_kwargs(field_name, model_field):
     if model_field.null and not isinstance(model_field, models.NullBooleanField):
         kwargs['allow_null'] = True
 
-    if model_field.blank and (isinstance(model_field, models.CharField) or
-                              isinstance(model_field, models.TextField)):
+    if model_field.blank and (isinstance(model_field, (models.CharField, models.TextField))):
         kwargs['allow_blank'] = True
 
     if isinstance(model_field, models.FilePathField):
@@ -193,9 +192,7 @@ def get_field_kwargs(field_name, model_field):
     # Ensure that max_length is passed explicitly as a keyword arg,
     # rather than as a validator.
     max_length = getattr(model_field, 'max_length', None)
-    if max_length is not None and (isinstance(model_field, models.CharField) or
-                                   isinstance(model_field, models.TextField) or
-                                   isinstance(model_field, models.FileField)):
+    if max_length is not None and (isinstance(model_field, (models.CharField, models.TextField, models.FileField))):
         kwargs['max_length'] = max_length
         validator_kwarg = [
             validator for validator in validator_kwarg