fix DnD border

src/scss/_dragdrop.scss

@@ -23,7 +23,7 @@
     margin-bottom: 17px;
   }
   
-    .uppy-DragDrop-container.is-dragdrop-supported {
+    .uppy-DragDrop--is-dragdrop-supported {
       border: 2px dashed;
       border-color: lighten($color-gray, 10%);
     }