Update duckdb index files

.gitattributes

@@ -1,3 +1,4 @@
 yonesuke--Ising2D/test/index.duckdb filter=lfs diff=lfs merge=lfs -text
 yonesuke--Ising2D/train/index.duckdb filter=lfs diff=lfs merge=lfs -text
 default/test/index.duckdb filter=lfs diff=lfs merge=lfs -text
+default/train/index.duckdb filter=lfs diff=lfs merge=lfs -text

default/train/index.duckdb

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:d2543cf848c702d73180982a497d0ea83d3cac827d2a79e46f0f5fda8c1f9354
+size 1060864