fix(event_sources): change partition and offset field types in KafkaEventRecord (#4515)

fix: Change partition and offset on the KafkaEventRecord to be an int type.

Author: scampbell5

aws_lambda_powertools/utilities/data_classes/kafka_event.py

@@ -15,12 +15,12 @@ def topic(self) -> str:
         return self["topic"]
 
     @property
-    def partition(self) -> str:
+    def partition(self) -> int:
         """The Kafka record parition."""
         return self["partition"]
 
     @property
-    def offset(self) -> str:
+    def offset(self) -> int:
         """The Kafka record offset."""
         return self["offset"]