Debian Jessie LTS reached End-Of-Life

As previously announced, the Debian Jessie LTS reached End-Of-Life on 30. June 2020. This means no further updates will be made to the packages and the repositories will go away at the end of July 2020. Edit: the repositories have been removed with the last PHP update, so they are already gone.

This has been awaited for too long, as removal of Debian Jessie LTS will allow upgrades in the packaging - most notably, I can now upgrade all packages to debhelper compatibility level 10 which brings many improvements and simplifications to the packaging process.