Update duckdb index files

.gitattributes

@@ -106,3 +106,4 @@ iwslt2017-ro-it/test/index.duckdb filter=lfs diff=lfs merge=lfs -text
 iwslt2017-ro-it/validation/index.duckdb filter=lfs diff=lfs merge=lfs -text
 iwslt2017-ro-nl/train/index.duckdb filter=lfs diff=lfs merge=lfs -text
 iwslt2017-ro-nl/test/index.duckdb filter=lfs diff=lfs merge=lfs -text
+iwslt2017-zh-en/train/index.duckdb filter=lfs diff=lfs merge=lfs -text

iwslt2017-zh-en/train/index.duckdb

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:fc6e8499d0babfb78ad7d5139b489ee9b55409c550e06545020bfb5777c5e55a
+size 25702400