Migrate to s6v3.
Note A future update will require Java 17. To prepare for that a message will be shown asking you to update your system accordingly. If you're running NZBHydra2 in docker you don't need to do anything.
Feature Set the environment variable NZBHYDRA_DISABLE_UPDATE to true to disable the NZBHydra update mechanism (similar as to when it's run inside docker). This can be used by package maintainers. See #809