Update duckdb index files

.gitattributes

@@ -4,3 +4,4 @@ citesum/citesum-test.parquet filter=lfs diff=lfs merge=lfs -text
 citesum/train/0000.parquet filter=lfs diff=lfs merge=lfs -text
 citesum/validation/0000.parquet filter=lfs diff=lfs merge=lfs -text
 citesum/test/0000.parquet filter=lfs diff=lfs merge=lfs -text
+citesum/train/index.duckdb filter=lfs diff=lfs merge=lfs -text

citesum/train/index.duckdb

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:8d9490011fd9d6e9b79cd679fc959fd49512c0f46a870f12f050eae0f47b313e
+size 316420096