Update ChangeLog.md

Author: aaustin

ChangeLog.md

@@ -1,14 +1,5 @@
 Branch iOS SDK change log
 
-- v0.12.3
-  * Fabric Answers integration
-  * Swift Testbed
-  * Retry in poor network conditions 
-  * Fix for Facebook calling openUrl from within the app
-  * Fix Fabric headers conflict
-  * Simplify Carthage project
-  * Fix framework headers visibility issue with BranchView
-
 - v0.12.3
   * Fabric Answers integration
   * Swift Testbed