Switching from package `xmldom` to `@xmldom/xmldom`, which resolves the security issue present in latest xmldom version 0.6.0:
GHSA-5fg8-2547-mr8q

The reason is that the maintainers were forced to switch to a scoped package since 0.7.0:
 xmldom/xmldom#271

No matter what version of node I used to try and run the normal `npm install`, I always received a warning about either old package lock file format or newer lock file version format.
So to avoid to many unrelated changes, I disabled the `postinstall` step locally and installed the root level using node v12 and the `mbTest` folder using node v16.
- When running the `npm run test` on the root level using node v12, there is a single failing test, but running them with node v16 works.So let's see what happens on CircleCI.

I'm happy to fix any regression we introduced, I just need help to understand how exactly the xmldom upgrade influences the failing test.

I'm one of the xmldom maintainers. Don't hesitate to ask me questions.