Fix bug in _compute method in horizonmetrics.py

horizonmetrics.py

@@ -124,7 +124,7 @@ class horizonmetrics(evaluate.Metric):
             self.slope_error_list.append(slope_error)
             self.midpoint_error_list.append(midpoint_error)
 
-    def _compute(self):
+    def _compute(self, *, predictions, references, **kwargs):
         """
         Compute the horizon error across the sequence.