Undo removed @Overloads from merge

Originally these were not overloads, but now they are.

Author: debonte

stubs/sklearn/metrics/_regression.pyi

@@ -107,6 +107,7 @@ def mean_squared_error(
 @deprecated(
     "`squared` is deprecated in 1.4 and will be removed in 1.6. Use `root_mean_squared_error` instead to calculate the root mean squared error."
 )
+@overload
 def mean_squared_error(
     y_true: MatrixLike | ArrayLike,
     y_pred: MatrixLike | ArrayLike,
@@ -146,6 +147,7 @@ def mean_squared_log_error(
 @deprecated(
     "`squared` is deprecated in 1.4 and will be removed in 1.6. Use `root_mean_squared_log_error` instead to calculate the root mean squared logarithmic error."
 )
+@overload
 def mean_squared_log_error(
     y_true: MatrixLike | ArrayLike,
     y_pred: MatrixLike | ArrayLike,