Make modules in dwmblocks start asynchronously like https://github.com/UtkarshVerma/dwmblocks-async

[JimPix1]

Modules starting asynchronously would be very useful to have and would make dwmblocks much faster, especially if there is a module that is slower than others (in my case it is my update checking module). It could be added similarly to https://github.com/UtkarshVerma/dwmblocks-async