To avoid inconsistencies with our other object models
This also fixes current storage build failure
[1] https://forge.softwareheritage.org/harbormaster/unit/view/744333/
[2] https://jenkins.softwareheritage.org/job/DSTO/job/tests/1530/console
@vlorentz didn't you open one diff about this (I don't find it)?
I kept a property called other in the content_metadata to regroup all metadata I wasn't able to translate to CodeMeta.
I see that you deleted this property, was it problematic with the type of output- keeping a codemeta.json output?