fix(accessibility): allow localisation on the string 'Default'

i18n/en/cosmic_settings.ftl

@@ -137,6 +137,7 @@ accessibility = Accessibility
     .high-contrast = High contrast mode
     .invert-colors = Invert Colors
     .color-filters = Color filters
+default = Default
 magnifier = Magnifier
     .controls = Or use these shortcuts: { $zoom_in ->
              [zero] {""}