tests: Panel brightness can range from 0 to 100 now

This is due to

    Librem5/linux-emcraft@6847961c

test_scripts/test_panel_brightness.py

 def test_panel_brightness():
     "Check if current panel brighness is in [0..9]"
     f = open("/sys/class/backlight/backlight_dsi/brightness")
-    assert int(f.read()) in range(0, 10)
+    assert int(f.read()) in range(0, 101)