Update duckdb index files

.gitattributes

@@ -199,3 +199,4 @@ 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
+marxism/dev/index.duckdb filter=lfs diff=lfs merge=lfs -text

marxism/dev/index.duckdb

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:f8668fd19f88be9fd67c78d159ff29b2c85530a3fa382f75d7ea1a1cca4fbf2a
+size 1060864