tweak Dashboard FileItem padding

packages/@uppy/dashboard/src/style.scss

@@ -623,7 +623,7 @@
     float: left;
     width: 140px;
     height: 170px;
-    margin: 5px 20px;
+    margin: 5px 15px;
     border: 0;
     background-color: initial;
     border-bottom: none;