NamespaceError: The operation is not allowed by Namespaces in XML. [XMLNS] Qualified name includes a prefix but the namespace is null.

[japel]

Describe the bug
When trying to specify xmlns: 'http://xml.datev.de/bedi/tps/document/v04.0' in my root element I get the following:
NamespaceError: The operation is not allowed by Namespaces in XML. [XMLNS] Qualified name includes a prefix but the namespace is null.

To Reproduce

let root = create({version: '1.0', encoding: 'utf-8'})
			.ele('archive', {
				version: '4.0',
				'xmlns:xsi': 'http://www.w3.org/2001/XMLSchema-instance',
				'xsi:schemaLocation': 'http://xml.datev.de/bedi/tps/document/v04.0 document_v040.xsd',
				xmlns: 'http://xml.datev.de/bedi/tps/document/v04.0'
			});
const xml = root.end({prettyPrint: true});

Expected behavior
It should be possible to specify xmlns attribute.

Version:

• node.js: [14.0.0]
• xmlbuilder2 [2.3.1]

Additional context
None.