Feature request: Reranker using fastembed

It would be nice to add the ability to use `fastembed` as an option.

[fastembed](https://github.com/qdrant/fastembed)
[How to rerank with fastembed](https://github.com/qdrant/fastembed?tab=readme-ov-file#-rerankers)
[Available models](https://qdrant.github.io/fastembed/examples/Supported_Models/?h=rerank#supported-rerank-cross-encoder-models)

The API would probably look like this

```python
ranker = Reranker('Xenova/ms-marco-MiniLM-L-6-v2', model_type='fastembed')
```