set msa as list; label as tensor2

fold_prediction_rag.py

@@ -262,7 +262,7 @@ class DownStreamTasks(datasets.GeneratorBasedBuilder):
             yield key, {
                 "seq":     seq,
                 "label":   label,
-                "msa":     "|".join(msa),
+                "msa":     msa,
                 "str_emb": str_emb
             }