Update duckdb index files

.gitattributes

@@ -74,3 +74,4 @@ cs-pt/train/index.duckdb filter=lfs diff=lfs merge=lfs -text
 cs-pl/train/index.duckdb filter=lfs diff=lfs merge=lfs -text
 cs-ro/train/index.duckdb filter=lfs diff=lfs merge=lfs -text
 cs-sk/train/index.duckdb filter=lfs diff=lfs merge=lfs -text
+cs-sl/train/index.duckdb filter=lfs diff=lfs merge=lfs -text

cs-sl/train/index.duckdb

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:b1ac5eb803b99f821508bee6784bd124b21802c577d41a973142f8f8ff3a04a5
+size 49295360