Debian Bullseye is EOL too (#2095)

Author: basil

src/main/resources/org/jenkinsci/test/acceptance/docker/fixtures/SvnContainer/Dockerfile

@@ -1,5 +1,5 @@
 # Sets up
-FROM debian:bullseye
+FROM debian/eol:bullseye
 
 # Viewvc is not part of bullseye repos anymore but oldstable https://github.com/viewvc/viewvc/issues/310
 RUN echo 'deb http://archive.debian.org/debian-security buster/updates main' > /etc/apt/sources.list.d/oldstable.list