Refactor user permissions task to use Ansible user module

ansible/installation/inst-docker.yaml

@@ -9,7 +9,9 @@
         - docker.io
       update_cache: yes
   - name: add user permissions
-    shell: "usermod -aG docker {{ ansible_env.SUDO_USER }}"
+    user:
+      name: "{{ ansible_env.SUDO_USER }}"
+      groups: docker
   - name: Reset ssh connection for changes to take effect
     meta: "reset_connection"
   - name: install python package manager