add: necessary assert statement; rem: unnecessary render resize in testing

src/testing.zig

@@ -109,7 +109,6 @@ pub fn expectContainerScreen(size: Point, container: *Container(event.SystemEven
     var renderer: Renderer = .init(allocator, size);
     defer renderer.deinit();
 
-    try renderer.resize(size);
     container.resize(size);
     container.reposition(.{});
     try renderer.render(Container(event.SystemEvent), container);