redfish: Set the permissions of redfish.conf at install time

Although typically we set the password using fu_plugin_set_secure_config_value()
or something like Ansible or Puppet -- the user could just edit the file with
vim and we still want the permissions set correctly.

plugins/redfish/meson.build

@@ -44,6 +44,7 @@ shared_module('fu_plugin_redfish',
 
 install_data(['redfish.conf'],
   install_dir: join_paths(sysconfdir, 'fwupd'),
+  install_mode: 'rw-r-----',
 )
 
 if get_option('tests')