Fix windows bug when using pytailwindcss.run directly

[Zwork101]

Right now, when pytailwind is ran via pytailwind.run, the env parameter that gets provided to subprocess.run is an empty dict. For example when I modified the pytailwind.__init__ file I got the following output:

print([str(bin_path)] + tailwindcss_cli_args, kwargs)
output = subprocess.run([str(bin_path)] + tailwindcss_cli_args, **kwargs)

['D:\\Programming Projects\\brim\\.venv\\Lib\\site-packages\\pytailwindcss\\bin\\latest\\tailwindcss', '--input', 'D:\\Programming Projects\\brim\\brimstone\\static\\_src\\input.css', '--output', 'D:\\Programming Projects\\brim\\brimstone\\static\\dist\\css\\output.css', '--minify', '--optimize', '--cwd', 'D:\\Programming Projects\\brim\\brimstone\\templates'] {'cwd': 'D:\\Programming Projects\\brim\\brimstone', 'env': {}, 'capture_output': True, 'check': True}

Because env is an empty dict, it causes the following error on Windows, and maybe Linux and Mac but I did not test it:

  File "D:\Programming Projects\brim\.venv\lib\site-packages\pytailwindcss\__init__.py", line 50, in run
    output = subprocess.run([str(bin_path)] + tailwindcss_cli_args, **kwargs)
  File "AppData\Roaming\uv\python\cpython-3.9.22-windows-x86_64-none\lib\subprocess.py", line 505, in run
    with Popen(*popenargs, **kwargs) as process:
  File "C:\Users\Zwork\AppData\Roaming\uv\python\cpython-3.9.22-windows-x86_64-none\lib\subprocess.py", line 951, in __init__
    self._execute_child(args, executable, preexec_fn, close_fds,
  File "AppData\Roaming\uv\python\cpython-3.9.22-windows-x86_64-none\lib\subprocess.py", line 1436, in _execute_child
    hp, ht, pid, tid = _winapi.CreateProcess(executable, args,
OSError: [WinError 87] The parameter is incorrect

The solution is very simple, just leave env as None, and everything works correctly.

[Zwork101]

For additional context, I'm using Python 3.9, and I'm on Windows 10.