Update duckdb index files

.gitattributes

@@ -9,3 +9,4 @@ realistic_difficult_x4/validation/index.duckdb filter=lfs diff=lfs merge=lfs -te
 unknown_x2/train/index.duckdb filter=lfs diff=lfs merge=lfs -text
 unknown_x2/validation/index.duckdb filter=lfs diff=lfs merge=lfs -text
 unknown_x4/train/index.duckdb filter=lfs diff=lfs merge=lfs -text
+unknown_x4/validation/index.duckdb filter=lfs diff=lfs merge=lfs -text

unknown_x4/validation/index.duckdb

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:682c9aaa8b54b790055eec59e1c4cf75d8137ec9aed8ccee7a14267c4e81b6a8
+size 1060864