fix: Support GID and UID on Windows

internal/fs/filesystem.go

@@ -82,12 +82,22 @@ func (f *FileSystem) mknode(dir bool, name string, perm os.FileMode) error {
 
 	uid, err := strconv.Atoi(usr.Uid)
 	if err != nil {
-		return err
+		// Some OSes like i.e. Windows don't support numeric UIDs, so use 0 instead
+		if err == strconv.ErrSyntax {
+			uid = 0
+		} else {
+			return err
+		}
 	}
 
 	gid, err := strconv.Atoi(usr.Gid)
 	if err != nil {
-		return err
+		// Some OSes like i.e. Windows don't support numeric GIDs, so use 0 instead
+		if err == strconv.ErrSyntax {
+			gid = 0
+		} else {
+			return err
+		}
 	}
 
 	groups, err := usr.GroupIds()