Tweak failure condition for field attributes expected to be strings

lib/ansible/playbook/base.py

@@ -235,7 +235,7 @@ class Base:
                 # and make sure the attribute is of the type it should be
                 value = getattr(self, name)
                 if value is not None:
-                    if attribute.isa == 'string' and not isinstance(value, string_types):
+                    if attribute.isa == 'string' and isinstance(value, (list, dict)):
                         raise AnsibleParserError("The field '%s' is supposed to be a string type, however the incoming data structure is a %s" % (name, type(value)), obj=self.get_ds())
 
     def copy(self):