Update xmldom to resolve security vulnerability

xmldom versions below 0.5.0 are deprecated due to https://github.com/xmldom/xmldom/security/advisories/GHSA-h6q6-9hqw-rwfv

Note there are some breaking changes between the current 0.1.x and 0.5.0: https://github.com/xmldom/xmldom/blob/master/CHANGELOG.md