Change pretty_progress to also display step 0

[dsignarius]

pretty_progress in util.cpp is called from stablediffusion.cpp to display the progress of steps along the process.

in stablediffusion.cpp it is called with a value of step=0, this is to signal that the first step has started and computation has started. then with the later steps the progress is displayed.
Without this then it is not displayed that the generation process has started and step 0 is in progress. On slower machines, those using cpu only or igpu, then this can lead to some confusion as to how far the whole process has gone.

pretty_progress in util.cpp contains the following lines:
if (step == 0) {
return;
}

yet, it is called explicitly with a value of 0, as described above.

suggest removing or commenting out the return above..
then the start of processing, when the first step commences will be displayed properly and the user will know.