Fix systemd version detection

Change "command" to "shell" in order for the pipe to work correctly

roles/docker/tasks/systemd.yml

@@ -12,7 +12,7 @@
   when: http_proxy is defined or https_proxy is defined
 
 - name: get systemd version
-  command: systemctl --version | head -n 1 | cut -d " " -f 2
+  shell: systemctl --version | head -n 1 | cut -d " " -f 2
   register: systemd_version
   when: not is_atomic
   changed_when: false