fix(dpmodel): correct return type annotations in dpa2 and hybrid descriptors

Co-authored-by: njzjz <9496702+njzjz@users.noreply.github.com>

Author: Copilot

deepmd/dpmodel/descriptor/dpa2.py

@@ -788,7 +788,7 @@ def set_stat_mean_and_stddev(
 
     def get_stat_mean_and_stddev(
         self,
-    ) -> tuple[tuple[Array, Array], list[Array]]:
+    ) -> tuple[list[Array], list[Array]]:
         """Get mean and stddev for descriptor."""
         mean_list = [self.repinit.mean, self.repformers.mean]
         stddev_list = [

deepmd/dpmodel/descriptor/hybrid.py

@@ -214,7 +214,7 @@ def set_stat_mean_and_stddev(
     def get_stat_mean_and_stddev(
         self,
     ) -> tuple[
-        list[tuple[Array, Array]],
+        list[Union[Array, list[Array]]],
         list[Union[Array, list[Array]]],
     ]:
         """Get mean and stddev for descriptor."""