Install pyreadstat using conda instead
```
> conda search pyreadstat -c conda-forge
Loading channels: done
# Name                       Version           Build  Channel
pyreadstat                     0.2.1  py36h301d43c_0  conda-forge
pyreadstat                     0.2.1  py37h301d43c_0  conda-forge
pyreadstat                     0.2.5  py36h301d43c_0  conda-forge
pyreadstat                     0.2.5  py37h301d43c_0  conda-forge
pyreadstat                     0.2.6  py36h301d43c_0  conda-forge
pyreadstat                     0.2.6  py37h301d43c_0  conda-forge
```

- [ ] closes #xxxx
- [ ] tests added / passed
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry
