feat: Add async support to InMemoryBM25Retriever and InMemoryEmbeddingRetriever
#840
| Job | Run time |
|---|---|
| 1m 37s | |
| 1m 29s | |
| 3m 13s | |
| 49s | |
| 15m 11s | |
| 3m 38s | |
| 48s | |
| 26m 45s |