Antora preview doesn't work if version is not specified in antora.yml

[alaindresse]

Antora allows using a refname projection as version from the antora playbook (see here on the antora docs).

Earlier in that page, the docs specify that

If you want the playbook to be able to control the value of the version key, don’t set the version key in the component version descriptor (antora.yml file). [bold added for this quote]

Issue:
If the version is excluded from the antoray.yml file, than the preview in vscode no longer works.

This is similar to the issue reported in #829, reporting that image preview did not work when version:true was configured. That issue was fixed in #871.