Update changelog for DynamoDB pagination fix from botocore (aws#9604)

Author: ashovlin

.changes/next-release/bugfix-dynamodb-83439.json

@@ -0,0 +1,5 @@
+{
+  "type": "bugfix",
+  "category": "``dynamodb``",
+  "description": "Correct Scan and Scanned Count values when resuming a scan or query with a ``--starting-token``"
+}