chore: update pylint settings to match changes in 2.5.0

Author: mattsb42-aws

src/aws_encryption_sdk/internal/validators.py

@@ -11,7 +11,7 @@
     pass
 
 
-def value_is_not_a_string(instance, attribute, value):
+def value_is_not_a_string(instance, attribute, value):  # pylint: disable=unused-argument
     # type: (Any, attr.Attribute, Any) -> None
     """Technically a string is an iterable containing strings.