Update duckdb index files

.gitattributes

@@ -199,3 +199,4 @@ 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/train/index.duckdb filter=lfs diff=lfs merge=lfs -text

singleop/train/index.duckdb

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:2c2ca51ba6f952af6a3ba818b211f5ecf7d54fa2cf77c5a6fd14bc059415a774
+size 1060864