src/lua: simplify volume checks using math.min and math.max

This is surprisingly a much simpler way of doing what I was doing. I
never knew one could do that.
Lua has some really interesting functions and I am really amazed by how
these small things simplify so many big things.

^.^ +1 for lua

lua/bar/audio.lua

@@ -22,16 +22,10 @@ return function()
       return string.format("%.0f%%", v * 100)
     end),
     on_scroll = function(_, event)
-      if speaker.volume <= 1 and speaker.volume >= 0 then
-        if event.delta_y < -1 then
-          speaker.volume = speaker.volume + 0.05
-        elseif event.delta_y > -1 then
-          speaker.volume = speaker.volume - 0.05
-        end
-      elseif speaker.volume > 1 then
-        speaker.volume = 1
-      elseif speaker.volume < 0 then
-        speaker.volume = 0
+      if event.delta_y < -1 then
+        speaker.volume = math.min(speaker.volume + 0.05, 1)
+      elseif event.delta_y > -1 then
+        speaker.volume = math.max(speaker.volume - 0.05, 0)
       end
     end,
     Widget.Box({