Latest release is fetched based on max ID instead of max pub_date

[jodal]

The latest release of a comic is found based on max id instead of max pub_date, which isn't always correct, though it is fast and generally works.

The offending code is in comics.core.utils.comic_releases.get_latest_releases().

[jodal]

This bug is only a problem when manually crawling older releases, which then gets the highest ID. As soon as a new release is out, the problem disappears, as the latest release has a higher ID than the old releases.

If a new release is not expected soon, a workaround is to delete the latest release and recrawl it, to ensure it gets the highest ID.

[jodal]

This bug is irrelevant for v2.0, as this functionality has been reimplemented.