Support the Jina AI jina-embeddings-v3 model

When trying to import the `jina-embeddings-v3` model I encountered the error described in https://huggingface.co/jinaai/jina-embeddings-v3/discussions/96. The stated fix on the discussion is to install the `flash-attn` package.

Support may depend on resolving https://github.com/elastic/eland/issues/721 first

Start by reproducing the import of jina-embeddings-v3 and read the linked Hugging Face discussion for the flash-attn requirement. Check elastic/eland#721 first, since the issue says support may depend on it; done means the model imports successfully without the reported error.

Written by the indexing model from the issue text.