Fatal Error in adding / editing an event

Hi there,

We seem to be running into an issue on a site that is running Simple Calendar. I know that the plugin has not been updated in a while, but figured I would post this here if you still are developing it.

Here is the error:

Fatal error: Declaration of CMB2_Type_Text_Datetime_Timestamp::render() must be compatible with CMB2_Type_Text::render($args = Array) in /wp-content/plugins/wp-simple-calendar/includes/cmb2/includes/types/CMB2_Type_Text_Datetime_Timestamp.php on line 13

Thanks,
Sean