Updated to Accordions 2.1.3, site went down

Hi,

For a few years now I've been using your Accordions plugin (on www.theleadershop.org) with no problem. Today (20 Oct 2018) I updated it to the latest version (2.1.3) and my site immediately went down, leaving this message:

Fatal error: Can't use method return value in write context in /home2/cepyl/public_html/theleadershop/wp-content/plugins/accordions/includes/class-WPAdminSettings.php on line 657

Fortunately I was able to get my hosting provider to deactivate the plugin, so the site came back up, but now I am concerned that if I re-activate the plugin, the site will go down AGAIN. What do you recommend that I do? I need the plugin to work so that I have accordions on pages such as:
http://theleadershop.org/programs/

THANK YOU in advance for your help,
-- Jim