Add merged changes to pendign change log
Adds 2703, to pending change log.
### SDK Features
### SDK Enhancements
+* Fixup SDK source formating, test error checking, and simplify type conervsions
+ * [#2703](https://github.com/aws/aws-sdk-go/pull/2703), [#2704](https://github.com/aws/aws-sdk-go/pull/2704), [#2705](https://github.com/aws/aws-sdk-go/pull/2705), [#2706](https://github.com/aws/aws-sdk-go/pull/2706), [#2707](https://github.com/aws/aws-sdk-go/pull/2707), [#2708](https://github.com/aws/aws-sdk-go/pull/2708)
### SDK Bugs
+* `aws/request`: Fix SDK error checking when seeking readers ([#2696](https://github.com/aws/aws-sdk-go/pull/2696))
+ * Fixes the SDK handling of seeking a reader to ensure errors are not lost, and are bubbled up.
+ * In several places the SDK ignored Seek errors when attempting to determine a reader's length, or rewinding the reader for retry attempts.
+ * Related to [#2525](https://github.com/aws/aws-sdk-go/issues/2525)
