if returned value for role is an array, use first element

This improves Keycloak compatibility as if Multivalued is set to false
in Mappers, return value will still be an array.

peertube-plugin-auth-openid-connect/main.js

@@ -239,7 +239,11 @@ async function handleCb (peertubeHelpers, settingsManager, req, res) {
 
     let role
     if (settings['role-property']) {
-      role = parseInt('' + userInfo[settings['role-property']], 10)
+      if (Array.isArray(settings['role-property'])){
+        role = parseInt('' + userInfo[settings['role-property']][0], 10);
+      } else {
+        role = parseInt('' + userInfo[settings['role-property']], 10)
+      }
     }
 
     let displayName