#394 Bug workdays invalid input

This whole sub makes more sense to me as a `map`, something like:

```perl
my $str_time = shift;
return lc join(
    '-',
    map {
        if   ($_ =~ /^\d$/) { '0' . $_ }    # Prepend '0' to single digits
        else                { $_ }          # Otherwise, use provided.
    } split(/,|-|\s|\//, $str_time));
```

Although, looking at it now, I may be wrong and yours might be more readable. :grin: