fix docker repo line

roles/docker/tasks/docker.yml

@@ -24,10 +24,16 @@
   ansible.builtin.apt_key:
     url: https://download.docker.com/linux/debian/gpg
 
+- name: determine architecture
+  changed_when: false
+  register: docker_arch
+  ansible.builtin.command:
+    cmd: dpkg --print-architecture
+
 - name: add docker repo
   become: true
   ansible.builtin.apt_repository:
-    repo: docker
+    repo: "deb [arch={{ docker_arch.stdout }}] https://download.docker.com/linux/debian"
     state: present
     update_cache: true