ci: migrate to latest llama-index version (#603)

Author: shahules786

src/ragas/testset/docstore.py

@@ -21,7 +21,7 @@
 from ragas.testset.utils import rng
 
 if t.TYPE_CHECKING:
-    from llama_index.readers.schema import Document as LlamaindexDocument
+    from llama_index.core.schema import Document as LlamaindexDocument
 
     from ragas.testset.extractor import Extractor