Ansible [DEPRECATION WARNING]: Using bare variables is deprecated. Update your playbooks so that the environment value uses the full variable syntax

If you recently upgraded Ansible and you are getting an error like:

[DEPRECATION WARNING]: Using bare variables is deprecated. Update your
playbooks so that the environment value uses the full variable syntax
('{{rbenv_plugins}}').
This feature will be removed in a future release.
Deprecation warnings can be disabled by setting deprecation_warnings=False in
ansible.cfg.

Where this your current playbook:

- name: Install plugins
  git: repo={{ item.git }} dest={{ rbenv_plugins_path }}/{{ item.name }} version={{ item.version }} accept_hostkey=yes
  sudo_user: '{{ user_name }}'
  with_items: rbenv_plugins

It needs to become:

- name: Install plugins
  git: repo={{ item.git }} dest={{ rbenv_plugins_path }}/{{ item.name }} version={{ item.version }} accept_hostkey=yes
  sudo_user: '{{ user_name }}'
  with_items: '{{ rbenv_plugins }}'

Note the last line, the variable for with_items must be in quotes and double curly braces.