chore(ui): update style of upload's img-preview

Author: xiejay97

packages/ui/src/styles/components/upload.scss

@@ -4,9 +4,9 @@
   display: none;
 
   @include e(picture-preview) {
-    max-width: 100%;
-    max-height: 100%;
-    margin: auto;
+    width: 100%;
+    height: 100%;
+    object-fit: contain;
     font-size: 0.9em;
   }