fix stdout exporter

Author: cijothomas

opentelemetry-stdout/src/metrics/transform.rs

@@ -230,7 +230,7 @@ impl<T: Into<DataValue> + Copy> From<&data::Sum<T>> for Sum {
 #[derive(Serialize, Debug, Clone)]
 #[serde(rename_all = "camelCase")]
 struct DataPoint {
-    attributes: AttributeSet,
+    attributes: Vec<KeyValue>,
     #[serde(serialize_with = "as_opt_human_readable")]
     start_time: Option<SystemTime>,
     #[serde(serialize_with = "as_opt_human_readable")]
@@ -253,7 +253,7 @@ fn is_zero_u8(v: &u8) -> bool {
 impl<T: Into<DataValue> + Copy> From<&data::DataPoint<T>> for DataPoint {
     fn from(value: &data::DataPoint<T>) -> Self {
         DataPoint {
-            attributes: AttributeSet::from(&value.attributes),
+            attributes: value.attributes.iter().map(Into::into).collect(),
             start_time_unix_nano: value.start_time,
             time_unix_nano: value.time,
             start_time: value.start_time,