Update prometheus_api_client/metric.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: 4n4nd

prometheus_api_client/metric.py

@@ -54,8 +54,10 @@ def __init__(self, metric, oldest_data_datetime=None):
             self.metric_values = metric.metric_values
             self.oldest_data_datetime = oldest_data_datetime
         else:
-            self.metric_name = metric["metric"].pop("__name__", None)
+            self.metric_name = metric["metric"].get("__name__", None)
             self.label_config = deepcopy(metric["metric"])
+            if "__name__" in self.label_config:
+                del self.label_config["__name__"]
             self.oldest_data_datetime = oldest_data_datetime
 
             # if it is a single value metric change key name