Update duckdb index files

.gitattributes

@@ -20,3 +20,4 @@ mnli/test_matched/index.duckdb filter=lfs diff=lfs merge=lfs -text
 mnli/test_mismatched/index.duckdb filter=lfs diff=lfs merge=lfs -text
 mnli/train/index.duckdb filter=lfs diff=lfs merge=lfs -text
 mnli/validation_matched/index.duckdb filter=lfs diff=lfs merge=lfs -text
+mnli/validation_mismatched/index.duckdb filter=lfs diff=lfs merge=lfs -text

mnli/validation_mismatched/index.duckdb

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:6ef926db474fcfc4206921d024a68e1c89d30cc08bcbbee6e8c7316b3ac89be4
+size 2895872