AboutCode Toolkit v11.0.0

* Add character support (at most 2 characters) for `attribute` field
* Strip empty newline characters when loading an inventory
* Catch invalid license_expression
* Update the specification to 3.3.2
* Support "declared_license_expression" and "other_license_expression"
* Updated "about_resource" to be an optional field
* Updated spec to v4.0.0 as moving `about_resource` from mandatory to optional