Error when scanning a `nul` file

I have a file `T:\Temp\rgworkspace\nul` on my disk.

And Vacuum now tells this during scanning:
```
Some(Error when scanning T:\Temp\rgworkspace: )The parameter is incorrect. : '\\.\nul'
System.IO.IOException: The parameter is incorrect. : '\\.\nul'
at System.IO.FileSystem.GetCreationTime(String )
at System.IO.File.GetCreationTimeUtc(String )
at Vacuum.Clean.getLastFileAccessDate@64.Invoke(AbsolutePath p)
at Vacuum.Clean.getLastFileAccessDate(AbsolutePath path) in D:\a\Vacuum\Vacuum\Vacuum\Clean.fs:line 64
at Vacuum.Clean.needToRemoveTopLevel@82.Invoke(AbsolutePath path)
at Microsoft.FSharp.Collections.SeqModule.ForAll[T](FSharpFunc`2 predicate, IEnumerable`1 source) in D:\a\_work\1\s\src\FSharp.Core\seq.fs:line 663
at Vacuum.Clean.needToRemoveTopLevel(Boolean verbose, DateTime date, AbsolutePath path) in D:\a\Vacuum\Vacuum\Vacuum\Clean.fs:line 79
```