Issue #3413783 by DYdave, Liam Morland: Updated module's...

https://www.drupal.org/project/block_class/issues/3413783

Updated module's maxlength_attributes config default value to 255 to fix schema validation error raised by tests:

Drupal\Core\Config\Schema\SchemaIncompleteException: Schema errors for block_class.settings with the following errors: block_class.settings:maxlength_attributes variable type is boolean but applied schema class is Drupal\Core\TypedData\Plugin\DataType\IntegerData