slider decimal display behavior is different on native vs web

```
eframe = { version = "0.28.1", default-features = false, features = [ "default_fonts", "glow", "wayland" ] }
egui = { version = "0.28.1", default-features = false, features = [ ] }
```

I have a simple slider like `Slider::new(_, 1.0..=50.).step_by(1.)`.

On desktop (Linux, Wayland) the displayed number of the slider does not show decimals. This is what I expect when I set the step to 1. On web (Linux, Firefox, eframe) the slider shows one decimal. I can fix this with `fixed_decimals(0)` but the point of the bug is that the behavior is inconsistent. It should be consistent.