stepSize adjustments are ignored if increment or decrement buttons are held in the sleep spinbox

**Describe the bug**
The stepSize behavior of the sleep spinbox can be overwritten by holding down either the increment or decrement arrow rather then pushing it repeatedly.

**To Reproduce**
Steps to reproduce the behavior:
1. Go to 'Options'
2. Set the 'Automatic sleep' value to something less than ten.
3. Press and hold the increment button until the value exceeds ten.
4. See the value continuing to increment by ones instead of by fives.

**Expected behavior**
The stepSize should increase by ones from 1-9, fives past 10, and by fifteens past 60, regardless of whether the buttons are held or tapped.

**Screenshots**
https://photos.app.goo.gl/ooJuxxw7TXQeLgmh9

**Version Information:**
- rM1 or rM2
- any OS
- as of commit 8fcc675