Add ansible.builtin qualification to become_method

ansible-lint 6.19.0 started complaining about this:

   schema[tasks]: 'become_method' must be one of the currently available
   values: ansible.builtin.runas, ansible.builtin.su,
           ansible.builtin.sudo, ansible.netcommon.enable,
           community.general.doas, community.general.dzdo,
           community.general.ksu, community.general.machinectl,
           community.general.pbrun, community.general.pfexec,
           community.general.pmrun, community.general.sesu,
           community.general.sudosu, containers.podman.podman_unshare