workspace-indicator: Round calculated preview sizes

While not strictly necessary, there's no reason to differ from the
copy in the window-list extension ...

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell-extensions/-/merge_requests/142>

(cherry picked from commit f5128e13f2)

extensions/workspace-indicator/extension.js

@@ -94,8 +94,8 @@ class WorkspaceLayout extends Clutter.LayoutManager {
             const childBox = new Clutter.ActorBox();
             const frameRect = child.metaWindow.get_frame_rect();
             childBox.set_size(
-                Math.min(frameRect.width, workArea.width) * hscale,
-                Math.min(frameRect.height, workArea.height) * vscale);
+                Math.round(Math.min(frameRect.width, workArea.width) * hscale),
+                Math.round(Math.min(frameRect.height, workArea.height) * vscale));
             childBox.set_origin(
                 Math.round(frameRect.x * hscale),
                 Math.round(frameRect.y * vscale));