Update duckdb index files

.gitattributes

@@ -16,3 +16,4 @@ ax/test/index.duckdb filter=lfs diff=lfs merge=lfs -text
 cola/test/index.duckdb filter=lfs diff=lfs merge=lfs -text
 cola/train/index.duckdb filter=lfs diff=lfs merge=lfs -text
 cola/validation/index.duckdb filter=lfs diff=lfs merge=lfs -text
+mnli/test_matched/index.duckdb filter=lfs diff=lfs merge=lfs -text

mnli/test_matched/index.duckdb

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:9c0ac23b206e352ea4a13c9337d2d3f6134ec37bd8b6056dbc8f803edd5d8bf2
+size 3158016