[data_release] "Unversioned" permissions granted with every version

[CamilleBeau]

Describe the bug
When adding version permissions for a user, the "Unversioned" permission is also granted to that user unintentionally.

To Reproduce
Steps to reproduce the behavior (attach screenshots if applicable):

1. Go to data_release
2. Make sure that there is at least one file uploaded without a version (version will show up as "Unversioned"), and at least one file uploaded under a specified version
3. Add permissions for a user to give them permission to the specified version
4. See that the user now has permission to both the specified version, and "Unversioned"

What did you expect to happen?
When adding permissions to one version for a user, that user should have permission to only that version, and not "Unversioned". "Unversioned" should only be granted to a user if it is added as a permission on its own.

[driusan]

PR was merged