Update duckdb index files

.gitattributes

@@ -7,3 +7,4 @@ economic-news/train/index.duckdb filter=lfs diff=lfs merge=lfs -text
 political-media-audience/train/index.duckdb filter=lfs diff=lfs merge=lfs -text
 political-media-bias/train/index.duckdb filter=lfs diff=lfs merge=lfs -text
 political-media-message/train/index.duckdb filter=lfs diff=lfs merge=lfs -text
+sentiment_nuclear_power/train/index.duckdb filter=lfs diff=lfs merge=lfs -text

sentiment_nuclear_power/train/index.duckdb

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:36fffde70da0e37de7d7490fca6ac9c1f15cd136e1960ad002d9207dc9b4c19f
+size 1060864