Update duckdb index files

.gitattributes

@@ -200,3 +200,4 @@ 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
 marxism/dev/index.duckdb filter=lfs diff=lfs merge=lfs -text
+mao_zedong_thought/dev/index.duckdb filter=lfs diff=lfs merge=lfs -text

mao_zedong_thought/dev/index.duckdb

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:72e55680496d231610233d5f02d37508c07c061abbeed9e8948c64b9a265f7f4
+size 1060864