Update duckdb index files

.gitattributes

@@ -117,3 +117,4 @@ iwslt2017-ko-en/validation/index.duckdb filter=lfs diff=lfs merge=lfs -text
 iwslt2017-nl-it/train/index.duckdb filter=lfs diff=lfs merge=lfs -text
 iwslt2017-ro-en/train/index.duckdb filter=lfs diff=lfs merge=lfs -text
 iwslt2017-ko-en/train/index.duckdb filter=lfs diff=lfs merge=lfs -text
+iwslt2017-zh-en/validation/index.duckdb filter=lfs diff=lfs merge=lfs -text

iwslt2017-zh-en/validation/index.duckdb

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:999750a2d5c9c4f5b4dd0ce2e0a7ac71fef3bf5162c9f3fc7e5d9076cc6bf98e
+size 1060864