tests: Move i386 test to debian:testing

i386/ubuntu:rolling is still eoan, :latest is still bionic, :devel is
uninstallable. Ubuntu does not really support i386 any more, so move
that test to Debian.

Author: martinpitt

.github/workflows/tests.yml

@@ -10,7 +10,7 @@ jobs:
           - apt-amd64/ubuntu:devel
           - apt-amd64/ubuntu:latest
           - apt-amd64/ubuntu:rolling
-          - apt-i386/ubuntu:rolling
+          - apt-i386/debian:testing
           - apt-amd64/debian:testing
           - dnf-fedora:latest
           - dnf-fedora:rawhide