Remove warn for Ansible 2.14 compatibility

Remove unnecessary warn parameter. Fixes #9.

Signed-off-by: Kevin Bowrin <kevinbowrin@cunet.carleton.ca>

roles/node_exporter/tasks/preflight.yml

@@ -62,8 +62,6 @@
 
 - name: Gather currently installed node_exporter version (if any)
   ansible.builtin.command: "{{ _node_exporter_binary_install_dir }}/node_exporter --version"
-  args:
-    warn: false
   changed_when: false
   register: __node_exporter_current_version_output
   check_mode: false