Update duckdb index files

.gitattributes

@@ -25,3 +25,4 @@ saved_model/**/* filter=lfs diff=lfs merge=lfs -text
 *.zip filter=lfs diff=lfs merge=lfs -text
 *.zstandard filter=lfs diff=lfs merge=lfs -text
 *tfevents* filter=lfs diff=lfs merge=lfs -text
+default/exercise_contest_valid/index.duckdb filter=lfs diff=lfs merge=lfs -text

default/exercise_contest_valid/index.duckdb

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:2bd57c0955bbf6a218e4198a63c70bbf3f52a27306fc0d0c1998663127c4062b
+size 36974592