Fix constant definition for SIMPLE_CALENDAR_VERSION (#685)

Author: rosinghal

google-calendar-events.php

@@ -21,7 +21,7 @@
 $this_plugin_path = trailingslashit(dirname(__FILE__));
 $this_plugin_dir = plugin_dir_url(__FILE__);
 $this_plugin_constants = [
-	'SIMPLE_CALENDAR_VERSION' => PACKAGE_VERSION,
+	'SIMPLE_CALENDAR_VERSION' => 'PACKAGE_VERSION',
 	'SIMPLE_CALENDAR_MAIN_FILE' => __FILE__,
 	'SIMPLE_CALENDAR_URL' => $this_plugin_dir,
 	'SIMPLE_CALENDAR_ASSETS' => $this_plugin_dir . 'assets/',