packages Enable serial moduls for luasockets

Maintainer: @flyn-org Compile tested: ath79/generic OpenWRT 23.05.3 Run tested: ath79/generic OpenWRT 23.05.3 Description: Includes the serial module for luasockets (which is already being built) in the final package. This allows using socket.select() on a serial port (eg /dev/ttyACM0) which is the easiest way to use a serial-port with coroutines. For instance copas can now be used via:

local copas = require("copas")
local serial = require("socket.serial")

copas.addthread(function()
        tty = copas.wrap(serial("/dev/ttyACM0"))
        l, e = tty:receivepartial()
        while not e do
                print(">" .. l)
                l, e = tty:receivepartial()
        end
end)
copas()