On Windows, wget is needed to install ESRGAN

[RadixSeven]

The code to install ESRGAN uses wget, which is unavailable by default in Windows.

I was able to diagnose and fix the problem myself by installing using Scoop, but SDD should check and notify users if wget is missing (or, better yet, not rely on it).

Here is the error that is generated if wget is not installed:

future: <Future finished exception=FileNotFoundError(2, 'The system cannot find the file specified', None, 2, None)>
Traceback (most recent call last):
  File "C:\Users\Eric\scoop\apps\python\3.11.3\Lib\concurrent\futures\thread.py", line 58, in run
    result = self.fn(*self.args, **self.kwargs)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "D:\Programs\StableDiffusionDeluxe\venv\Lib\site-packages\flet_core\page.py", line 950, in wrapper
    handler(*args)
  File "D:\Programs\StableDiffusionDeluxe\venv\Stable-Diffusion-Deluxe.py", line 2274, in run_installers
    get_ESRGAN(page)
  File "D:\Programs\StableDiffusionDeluxe\venv\Stable-Diffusion-Deluxe.py", line 24963, in get_ESRGAN
    run_sp(f"wget {model_url} -P experiments/pretrained_models --quiet", cwd=ESRGAN_folder)
  File "D:\Programs\StableDiffusionDeluxe\venv\Stable-Diffusion-Deluxe.py", line 62, in run_sp
    returned = subprocess.run(cmd_list, stdout=subprocess.PIPE, env=env, **cwd_arg).stdout.decode('utf-8')
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Eric\scoop\apps\python\3.11.3\Lib\subprocess.py", line 548, in run
    with Popen(*popenargs, **kwargs) as process:
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Eric\scoop\apps\python\3.11.3\Lib\subprocess.py", line 1024, in __init__
    self._execute_child(args, executable, preexec_fn, close_fds,
  File "C:\Users\Eric\scoop\apps\python\3.11.3\Lib\subprocess.py", line 1509, in _execute_child
    hp, ht, pid, tid = _winapi.CreateProcess(executable, args,
                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
FileNotFoundError: [WinError 2] The system cannot find the file specified