Replace backslash with forward slash

[masenf]

I'm not crazy about this fix, but it's a short term solution.

Ideally we can rewrite the path handling stuff using pathlib, and then get these uri-style paths via as_posix API.

CI runs still failing though: https://github.com/reflex-dev/reflex/actions/runs/7566517188/job/20604025206?pr=2414#step:8:2697

[Error: EMFILE: too many open files, open 
'D:\a\reflex\reflex\reflex-web\.web\node_modules\next\dist\server\require-hook.
js'] {
  errno: -4066,
  code: 'EMFILE',
  syscall: 'open',
  path: 
'D:\\a\\reflex\\reflex\\reflex-web\\.web\\node_modules\\next\\dist\\server\\req
uire-hook.js'
}

I'm seeing this even on my local windows VM as well.