HybridRetriever does not respect cutoff when calling sub-retrievers and the merger

[jacobvsdanniel]

In HybridRetriever.search:

        sparse_results = self.sparse_retriever.search(query, False, 1_000)
        dense_results = self.dense_retriever.search(query, False, 1_000)
        hybrid_results = self.merger.fuse([sparse_results, dense_results])

cutoff is not passed down.

potential fix:

        sparse_results = self.sparse_retriever.search(query, False, cutoff)
        dense_results = self.dense_retriever.search(query, False, cutoff)
        hybrid_results = self.merger.fuse([sparse_results, dense_results], cutoff)