misc: clean up changelog (#1017)

Author: lauzadis

.changes/ee74d8c0-697e-4ca2-95c9-d0285876c71a.json

@@ -4,7 +4,6 @@
 
 ### Features
 * [#583](https://github.com/awslabs/aws-sdk-kotlin/issues/583) Make user-supplied region available to config resolution providers
-* [#745](https://github.com/awslabs/aws-sdk-kotlin/issues/745) Validate returned content length on S3 `GetObject` responses.
 * [#1004](https://github.com/awslabs/aws-sdk-kotlin/issues/1004) Make RegionProviderChain accept a list of RegionProvider
 
 ### Fixes