sentencesplitter has changed namespaces

Author: Richard Kuo (Onyx)

backend/onyx/indexing/chunker.py

@@ -135,7 +135,7 @@ def __init__(
         mini_chunk_size: int = MINI_CHUNK_SIZE,
         callback: IndexingHeartbeatInterface | None = None,
     ) -> None:
-        from llama_index.text_splitter import SentenceSplitter
+        from llama_index.core.node_parser import SentenceSplitter
 
         self.include_metadata = include_metadata
         self.chunk_token_limit = chunk_token_limit