Fixes the following warning
2023-05-21 13:03:02 W: awesome: wibox.widget.background has been renamed to wibox.container.background.
stack traceback:
/usr/share/awesome/lib/gears/debug.lua:113: in function 'gears.debug.deprecate'
/usr/share/awesome/lib/gears/debug.lua:164: in local 'layout'
/usr/share/awesome/lib/wibox/widget/base.lua:745: in upvalue 'drill'
/usr/share/awesome/lib/wibox/widget/base.lua:778: in upvalue 'drill'
/usr/share/awesome/lib/wibox/widget/base.lua:818: in function 'wibox.setup'
...nfig/awesome/awesome-wm-widgets/pacman-widget/pacman.lua:227: in upvalue 'callback'
/usr/share/awesome/lib/awful/widget/watch.lua:88: in function </usr/share/awesome/lib/awful/widget/watch.lua:87>
Madhur Ahuja
James Arrowsmith