This fixes the case where the version referenced within the package.json is
more specific (e.g. '0.1.1-alpha.14+ac08282d') than the version referenced in
the 'time' dictionary (e.g. '0.1.1-alpha.14'). Without this, the current
loading fails with a key error on the specific version.
This matches what was done in the prior loader-npm version [1]
[1] https://forge.softwareheritage.org/source/swh-loader-npm/browse/master/swh/loader/npm/client.py$84-91