Allow user to specify desired release when generating lists

[guiscaranse]

For Ubuntu-based spins (such as ElementaryOS), apt-mirror-update will raise a error due to the platform release name is different from Ubuntu.

For example: Running it on ElementaryOS will raise a ValueError: The string 'hera' doesn't match a known Debian or Ubuntu release!

Allowing users to overwrite the release when running apt-mirror-updater would fix this issue, for example: apt-mirror-updater --release=bionic

[xolox]

Hi Guilherme and thanks for the feedback. I've just published apt-mirror-updater 7.2 which properly recognizes and supports Elementary OS. It knows which Elementary OS releases correspond to which Ubuntu releases so no release has to be specified.