add containerd.io to dpkg_selection

`containerd.io` is the companion package of `docker-ce` and is the
proper package name. This is needed to avoid apt upgrade/dist-upgrade
from breaking kubernetes.

roles/container-engine/docker/tasks/main.yml

@@ -92,7 +92,7 @@
   when: ansible_pkg_mgr == 'apt'
   changed_when: false
   with_items:
-    - containerd
+    - "{{ containerd_package }}"
     - docker-ce
     - docker-ce-cli
 
@@ -127,6 +127,7 @@
   when: ansible_pkg_mgr == 'apt'
   changed_when: false
   with_items:
+    - "{{ containerd_package }}"
     - docker-ce
     - docker-ce-cli