Update duckdb index files

.gitattributes

@@ -11,3 +11,4 @@ PHP-snippet-level/xlcost-text-to-code-train.parquet filter=lfs diff=lfs merge=lf
 Python-program-level/xlcost-text-to-code-train.parquet filter=lfs diff=lfs merge=lfs -text
 Python-snippet-level/xlcost-text-to-code-train.parquet filter=lfs diff=lfs merge=lfs -text
 C++-program-level/test/index.duckdb filter=lfs diff=lfs merge=lfs -text
+C-snippet-level/validation/index.duckdb filter=lfs diff=lfs merge=lfs -text

C-snippet-level/validation/index.duckdb

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:af708e33a398fa3e1414a6a0d2625e27a14e26d722e405f17a540c8e494fe841
+size 1060864