Pinning requirements

I had reason to run one of these again, and this currently worked

```python
Flask==1.1.1
requests==2.20.0
#urllib3==1.26.5
PyYAML==5.4
setuptools-scm==3.3.3
gevent==1.4.0
gunicorn==20.0.4
spacy==2.2.4
jinja2<3.1.0
itsdangerous==2.0.1
werkzeug==2.0.3
scikit-learn==0.21.3
```