Update duckdb index files

.gitattributes

@@ -322,3 +322,4 @@ serbian_latin/test/index.duckdb filter=lfs diff=lfs merge=lfs -text
 serbian_latin/train/index.duckdb filter=lfs diff=lfs merge=lfs -text
 serbian_latin/validation/index.duckdb filter=lfs diff=lfs merge=lfs -text
 sinhala/test/index.duckdb filter=lfs diff=lfs merge=lfs -text
+sinhala/train/index.duckdb filter=lfs diff=lfs merge=lfs -text

sinhala/train/index.duckdb

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:9d96aaf41a5e91e6f400bcf8427077414c4b5de911dad1ead58caa3b54a0d04e
+size 12595200