API docs broken on read the docs

### Environment
* DiffSync version: Current version on read the docs

### Observed Behavior

[This](diffsync.readthedocs.io/en/latest/api/diffsync.html) doesn't render correctly.

### Expected Behavior

It should render correctly.

### Steps to Reproduce
1. Go to https://diffsync.readthedocs.io/en/latest/api/diffsync.html
