Revisit why we are skipping some versions in gentoo importer

[TG1999]

    ```suggestion
    #TODO : Revisit why we are skipping some versions in gentoo importer 
    skip_versions = {"1.3*", "7.3*", "7.4*"}

_Originally posted by @TG1999 in https://github.com/nexB/vulnerablecode/pull/1056#discussion_r1063559608_