v0.3.1 not available for python 3.8 on pypi.org

Would it be possible to build the 0.3.1 version for python 3.8 as well and make it available on pypi.org?

```
➜  ~ docker run -ti python:3.8 /bin/bash
root@9c5eb8a054cd:/# pip install sktime==0.3.1
ERROR: Could not find a version that satisfies the requirement sktime==0.3.1 (from versions: 0.1.dev0, 0.1.0, 0.2.0, 0.3.0)
ERROR: No matching distribution found for sktime==0.3.1
```