--stdin does not work in msys2

Validator fails when using --stdin on MSYS2 (possibly on windows in general)

EDIT: bug occurs on:

• MSYS2
• Git bash (MinGW64)
• cmd
• PowerShell

Reduced test-case

echo '' | npm exec html-validate -- --stdin

Expected result

No error

Actual result

Validator crashed when parsing "/dev/stdin"
Caught exception:
  Error: ENOENT: no such file or directory, open '/dev/stdin'
      at Object.openSync (fs.js:498:3)
      at Object.readFileSync (fs.js:394:35)
      at ResolvedConfig.transformFilename (C:\path\to\repo\node_modules\html-validate\dist\cjs\core.js:9773:45)
      at HtmlValidate.validateFile (C:\path\to\repo\node_modules\html-validate\dist\cjs\core.js:11468:33)
      at C:\path\to\repo\node_modules\html-validate\dist\cjs\html-validate.js:60:33
      at Array.map (<anonymous>)
      at lint (C:\path\to\repo\node_modules\html-validate\dist\cjs\html-validate.js:58:27)
      at Object.<anonymous> (C:\path\to\repo\node_modules\html-validate\dist\cjs\html-validate.js:239:24)
      at Module._compile (internal/modules/cjs/loader.js:1072:14)
      at Object.Module._extensions..js (internal/modules/cjs/loader.js:1101:10) {
    errno: -4058,
    syscall: 'open',
    code: 'ENOENT',
    path: '/dev/stdin'
  }
This is a bug in html-validate-6.3.1.
Please file a bug at https://gitlab.com/html-validate/html-validate/issues/new?issuable_template=Bug
and include this message in full and if possible the content of the
file being parsed (or a reduced testcase).