Fix silent fail for UNC path files on Windows

Describe the issue. Is it a bug or a feature request (new rule, new option, etc.)?

stylelint doesn't work with network file paths e.g. stylelint \\192.168.0.1\httpdocs\public\css\, local file paths e.g. stylelint c:\httpdocs\public\css\ work fine.

What CSS is needed to reproduce this issue?

any

What stylelint configuration is needed to reproduce this issue?

{
  "extends": "C:\\Users\\\\user\\AppData\\Roaming\\npm\\node_modules\\stylelint-config-recommended"
}

Which version of stylelint are you using?

8.3.1

How are you running stylelint: CLI, PostCSS plugin, Node API?

CLI with stylelint \\192.168.0.1\httpdocs\public\css\

Does your issue relate to non-standard syntax (e.g. SCSS, nesting, etc.)?

No

What did you expect to happen?

The same as with local file.

What actually happened (e.g. what warnings or errors you are getting)?

No errors or warnings, no output at all, the same as if I run stylelint c:\httpdocs\public\css\nonexistent.css