1.5 is not released to PyPI.

Release 1.5 is not in PyPI so versions are stuck at 1.4 via `pip`. Can be replicated by running:

```
pip install workdays==1.5
```

Which gives the expected error of:

```
Collecting workdays==1.5
  Could not find a version that satisfies the requirement workdays==1.5 (from versions: 1.0, 1.2, 1.3, 1.4)
No matching distribution found for workdays==1.5
```