Write docker.list as a single line

apt_repository only adds lines, so the repo line of the previous Debian release stayed in the file after a dist upgrade.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tasks/main.yml

@@ -24,11 +24,14 @@
     dest: /etc/apt/keyrings/docker.asc
     mode: '0644'
 
+# write the whole file so repo lines of older releases do not linger
 - name: Add Docker repository
-  apt_repository:
-    repo: "deb [arch={{ docker_apt_arch[ansible_architecture] | default(ansible_architecture) }} signed-by=/etc/apt/keyrings/docker.asc] https://download.docker.com/linux/debian {{ ansible_distribution_release }} stable"
-    state: present
-    filename: docker
+  copy:
+    dest: /etc/apt/sources.list.d/docker.list
+    content: "deb [arch={{ docker_apt_arch[ansible_architecture] | default(ansible_architecture) }} signed-by=/etc/apt/keyrings/docker.asc] https://download.docker.com/linux/debian {{ ansible_distribution_release }} stable\n"
+    owner: root
+    group: root
+    mode: "0644"
 
 - name: Update apt cache
   apt: