Switch tests to use Molecule.

tasks/docker-users.yml

@@ -3,5 +3,5 @@
   user:
     name: "{{ item }}"
     groups: docker
-    append: yes
+    append: true
   with_items: "{{ docker_users }}"

tasks/setup-Debian.yml

@@ -29,11 +29,11 @@
 - name: Add Docker apt key (alternative for older systems without SNI).
   shell: "curl -sSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -"
   args:
-    warn: no
+    warn: false
   when: add_repository_key is failed
 
 - name: Add Docker repository.
   apt_repository:
     repo: "{{ docker_apt_repository }}"
     state: present
-    update_cache: yes
+    update_cache: true