Update RELEASE.CHANGELOG.md

Author: ashovlin

RELEASE.CHANGELOG.md

@@ -1,6 +1,11 @@
+### Release 2024-03-12
+* **Amazon.Lambda.DynamoDBEvents (3.1.1)**
+  * Better handle empty `AttributeValue` objects when serializing `DynamoDBEvent` objects to JSON.
+
 ### Release 2024-03-04
 * **Amazon.Lambda.DynamoDBEvents (3.1.0)**
   * Added `ToJson` which can be used to convert `DynamoDBEvent` objects to the higher-level document and object persistence classes in the AWS SDK.
+
 ### Release 2024-02-22
 * **Amazon.Lambda.Templates (7.0.0)**
   * Updated templates to target .NET 8