Update duckdb index files

.gitattributes

@@ -2,3 +2,4 @@ allenai--cochrane_dense_oracle/parquet-validation.parquet filter=lfs diff=lfs me
 allenai--cochrane_dense_oracle/parquet-train.parquet filter=lfs diff=lfs merge=lfs -text
 allenai--cochrane_dense_oracle/test/index.duckdb filter=lfs diff=lfs merge=lfs -text
 allenai--cochrane_dense_oracle/train/index.duckdb filter=lfs diff=lfs merge=lfs -text
+allenai--cochrane_dense_oracle/validation/index.duckdb filter=lfs diff=lfs merge=lfs -text

allenai--cochrane_dense_oracle/validation/index.duckdb

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:1459b9ee77b42f193b7789bf08adf72fc76e82f74f7e403df793d85bea21d6a0
+size 10235904