Update duckdb index files

.gitattributes

@@ -5,3 +5,4 @@ bicubic_x4/validation/index.duckdb filter=lfs diff=lfs merge=lfs -text
 bicubic_x8/train/index.duckdb filter=lfs diff=lfs merge=lfs -text
 bicubic_x8/validation/index.duckdb filter=lfs diff=lfs merge=lfs -text
 realistic_difficult_x4/train/index.duckdb filter=lfs diff=lfs merge=lfs -text
+realistic_difficult_x4/validation/index.duckdb filter=lfs diff=lfs merge=lfs -text

realistic_difficult_x4/validation/index.duckdb

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:b5f38a4c7d4e355d96c86f71759c0a7707524967bccdf36a31eddbf299528f7b
+size 1060864