apps: settings: Fix initial slider value

When the Settings app is launched, it shows the "Mid" text (this is
correct), but the slider is at the lowest position. After moving the
slider it functions correctly, so this fix is mostly cosmetic.

Signed-off-by: kozova1 <mug66kk@gmail.com>

wasp/apps/settings.py

@@ -19,6 +19,7 @@ class SettingsApp():
 
     def __init__(self):
         self._slider = wasp.widgets.Slider(3, 10, 90)
+        self._slider.value = wasp.system.brightness - 1
 
     def foreground(self):
         self._draw()