Update duckdb index files

.gitattributes

@@ -198,3 +198,4 @@ simuleq/test/index.duckdb filter=lfs diff=lfs merge=lfs -text
 ood/validation/index.duckdb filter=lfs diff=lfs merge=lfs -text
 simuleq/train/index.duckdb filter=lfs diff=lfs merge=lfs -text
 simuleq/validation/index.duckdb filter=lfs diff=lfs merge=lfs -text
+singleop/test/index.duckdb filter=lfs diff=lfs merge=lfs -text

singleop/test/index.duckdb

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:dcdf14b9ef7bbb8f63557d08cc449ba88b394061c0893a70b4aab79c2c30dd07
+size 1060864