Maintenance: Drop packager.io support for Debian 11.

Approved-by: Martin Gruner <mg@zammad.com>

.github/workflows/packager.io.yaml

@@ -22,7 +22,6 @@ jobs:
       fail-fast: false
       matrix:
         target:
-          - debian:11
           - debian:12
           - debian:13
           - el:9

.gitlab/ci/test/packager.io.yml

@@ -27,4 +27,4 @@ packager.io:
   extends: [.packager.io]
   parallel:
     matrix:
-      - DISTRO: [debian-11, debian-12, debian-13, ubuntu-22.04, ubuntu-24.04, ubuntu-26.04, rhel-9, rhel-10, sles-15, sles-16.0]
+      - DISTRO: [debian-12, debian-13, ubuntu-22.04, ubuntu-24.04, ubuntu-26.04, rhel-9, rhel-10, sles-15, sles-16.0]

.pkgr.yml

@@ -35,20 +35,6 @@ targets:
       # EPEL packages can only be installed after enabling the EPEL repo (see before.sh).
       - epel-release
       - shared-mime-info
-  debian-11:
-    dependencies:
-      - curl
-      - elasticsearch|elasticsearch-oss
-      - nginx|apache2
-      - postgresql
-      - libimlib2
-      - libjemalloc2
-      - shared-mime-info
-      - redis-server
-    build_dependencies:
-      - libimlib2
-      - libimlib2-dev
-      - shared-mime-info
   debian-12:
     dependencies:
       - curl

BREAKING_CHANGES.md

@@ -2,6 +2,20 @@
 
 ## Upcoming releases
 
+### Debian 11 will no longer be supported
+
+**Who is affected?** Admins of instances installed from the Zammad package repository on Debian 11
+("bullseye").
+
+Debian 11 reached its LTS end of life on 2026-08-31 and no longer receives security updates. A future
+release will therefore no longer be built for it, and the package repository will provide no Debian 11
+packages for that release and later ones. Zammad 7.1 keeps receiving Debian 11 packages until it goes
+out of maintenance.
+
+⚠️ Upgrade the operating system to a supported Debian release before updating.
+
+**Related issue:** [#6360](https://github.com/zammad/zammad/issues/6360)
+
 ### Inline attachments will be listed separately in ticket article API responses
 
 **Who is affected?** Integrations that read inline images from the `attachments` list of ticket article