Fixed file extension issue

web/Photo/backend/listFolder.js

@@ -6,6 +6,7 @@ function getExt(filename){
 
 function isImage(filename){
     var ext = getExt(filename);
+    ext = ext.toLowerCase();
     if (ext == "png" || ext == "jpg" || ext == "jpeg" || ext == "webp"){
         return true;
     }