Update duckdb index files

.gitattributes

@@ -57,3 +57,4 @@ validation.csv filter=lfs diff=lfs merge=lfs -text
 test.csv filter=lfs diff=lfs merge=lfs -text
 stacked-summaries--stacked-xsum-1024/test/index.duckdb filter=lfs diff=lfs merge=lfs -text
 stacked-summaries--stacked-xsum-1024/validation/index.duckdb filter=lfs diff=lfs merge=lfs -text
+stacked-summaries--stacked-xsum-1024/train/index.duckdb filter=lfs diff=lfs merge=lfs -text

stacked-summaries--stacked-xsum-1024/train/index.duckdb

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:dd00e739d5e75b786ae8fb662268b592f1e81aa6d06d130e90267ec54662cdee
+size 1889021952