Update sentry tracer

Author: buenaflor

dart/lib/src/sentry_tracer.dart

@@ -109,18 +109,24 @@ class SentryTracer extends ISentrySpan {
       }
 
       var _rootEndTimestamp = commonEndTimestamp;
+
+      // Trim the end timestamp of the transaction to the very last timestamp of child spans
       if (_trimEnd && children.isNotEmpty) {
-        final childEndTimestamps = children
-            .where((child) => child.endTimestamp != null)
-            .map((child) => child.endTimestamp!);
-
-        if (childEndTimestamps.isNotEmpty) {
-          final oldestChildEndTimestamp =
-              childEndTimestamps.reduce((a, b) => a.isAfter(b) ? a : b);
-          if (_rootEndTimestamp.isAfter(oldestChildEndTimestamp)) {
-            _rootEndTimestamp = oldestChildEndTimestamp;
+        DateTime? latestEndTime;
+
+        for (var child in children) {
+          final childEndTimestamp = child.endTimestamp;
+          if (childEndTimestamp != null) {
+            if (latestEndTime == null ||
+                childEndTimestamp.isAfter(latestEndTime)) {
+              latestEndTime = child.endTimestamp;
+            }
           }
         }
+
+        if (latestEndTime != null) {
+          _rootEndTimestamp = latestEndTime;
+        }
       }
 
       // the callback should run before because if the span is finished,