Update duckdb index files

.gitattributes

@@ -57,3 +57,4 @@ UKPLab--liar/train/index.duckdb filter=lfs diff=lfs merge=lfs -text
 UKPLab--liar/validation/index.duckdb filter=lfs diff=lfs merge=lfs -text
 default/test/index.duckdb filter=lfs diff=lfs merge=lfs -text
 default/train/index.duckdb filter=lfs diff=lfs merge=lfs -text
+default/validation/index.duckdb filter=lfs diff=lfs merge=lfs -text

default/validation/index.duckdb

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:6194879f4ac37841489a982170a46631fdd654d2f622405666bbfbc9eea487c1
+size 1323008