Update duckdb index files

.gitattributes

@@ -17,3 +17,4 @@ bicubic_x2/validation/index.duckdb filter=lfs diff=lfs merge=lfs -text
 realistic_wild_x4/train/index.duckdb filter=lfs diff=lfs merge=lfs -text
 realistic_wild_x4/validation/index.duckdb filter=lfs diff=lfs merge=lfs -text
 unknown_x3/train/index.duckdb filter=lfs diff=lfs merge=lfs -text
+unknown_x3/validation/index.duckdb filter=lfs diff=lfs merge=lfs -text

unknown_x3/validation/index.duckdb

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:c753df665720a87629ae0b1b9b9e4926f85594e286e8d5503884bc4ff97eb556
+size 1060864