Prevent warning "The following packages cannot be authenticated"
This warning happens sometimes on some of our servers when the microupdates are installed automatically (I guess). This also happens when upgrading the underlying Debian version (yes, I know this is unfortunately not the preferred Parallels way).
The packages don´t seem to be signed or the key missing (or is it already possible to import the key???), so this could be improved.
Can be easily fixed with help of KB article https://support.plesk.com/hc/en-us/articles/115000603309-Plesk-upgrade-failed-WARNING-The-following-packages-cannot-be-authenticated-