Update duckdb index files

.gitattributes

@@ -198,3 +198,4 @@ mao_zedong_thought/test/index.duckdb filter=lfs diff=lfs merge=lfs -text
 mao_zedong_thought/val/index.duckdb filter=lfs diff=lfs merge=lfs -text
 marxism/test/index.duckdb filter=lfs diff=lfs merge=lfs -text
 middle_school_physics/val/index.duckdb filter=lfs diff=lfs merge=lfs -text
+modern_chinese_history/test/index.duckdb filter=lfs diff=lfs merge=lfs -text

modern_chinese_history/test/index.duckdb

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:92fa41fd6b050f43b6dcd71d79f250592559fd1a6760f2ab5656d4f8d9f795d8
+size 1060864