Update widget.js

the additional slash causes this widget to fail.

this works:  http://host:port/api?apikey=***&mode=test&output=json
this does not:  http://host:port/api/?apikey=***&mode=test&output=json

src/widgets/sabnzbd/widget.js

@@ -1,7 +1,7 @@
 import genericProxyHandler from "utils/proxy/handlers/generic";
 
 const widget = {
-  api: "{url}/api/?apikey={key}&output=json&mode={endpoint}",
+  api: "{url}/api?apikey={key}&output=json&mode={endpoint}",
   proxyHandler: genericProxyHandler,
 
   mappings: {