Fix broken image downscale TypeError

[w-e-w]

Fx broken image downscale caused by reword settings for 4chan export, remove unneded try/excepts, add try/except for actually saving JPG which also remove the float to int casting of opts.target_side_length
as resize size can only be integer tuple this raises an error causing the downscale to fail

Error completing request
Arguments: (0, <PIL.Image.Image image mode=RGB size=768x1024 at 0x20703F08250>, None, '', '', True, 0, 4, 512, 512, True, 'R-ESRGAN 4x+ Anime6B', 'None', 0, 0, 0, 0) {}
Traceback (most recent call last):
  File "B:\Documents\GitHub\stable-diffusion-webui\modules\call_queue.py", line 56, in f
    res = list(func(*args, **kwargs))
  File "B:\Documents\GitHub\stable-diffusion-webui\modules\call_queue.py", line 37, in f
    res = func(*args, **kwargs)
  File "B:\Documents\GitHub\stable-diffusion-webui\modules\postprocessing.py", line 70, in run_postprocessing
    images.save_image(pp.image, path=outpath, basename=basename, seed=None, prompt=None, extension=opts.samples_format, info=infotext, short_filename=True, no_prompt=True, grid=False, pnginfo_section_name="extras", existing_info=existing_pnginfo, forced_filename=None)
  File "B:\Documents\GitHub\stable-diffusion-webui\modules\images.py", line 587, in save_image
    image = image.resize((image.width * opts.target_side_length // image.height, opts.target_side_length), LANCZOS)
  File "B:\Documents\GitHub\stable-diffusion-webui\venv\lib\site-packages\PIL\Image.py", line 2192, in resize
    return self._new(self.im.resize(size, resample, box))
TypeError: 'float' object cannot be interpreted as an integer

This PR fixes the issue
yes I could just typed casted as I did before
but since I'm bored I used round() for more accurate approximation

note: the round() functions will returns int type
Return number rounded to ndigits precision after the decimal point. If ndigits is omitted or is None, it returns the nearest integer to its input.

why also use round() on opts.target_side_length and not int()?
for those thick headed people that decides to use a non integer value

[andyxr]

"thick headed people"?