Prepare changelog for v1.3.0

Author: RiotRobot

CHANGELOG.md

@@ -1,3 +1,9 @@
+Changes in [1.3.0](https://github.com/matrix-org/matrix-react-sdk/releases/tag/v1.3.0) (2019-07-08)
+===================================================================================================
+[Full Changelog](https://github.com/matrix-org/matrix-react-sdk/compare/v1.3.0-rc.1...v1.3.0)
+
+No changes since rc.1
+
 Changes in [1.3.0-rc.1](https://github.com/matrix-org/matrix-react-sdk/releases/tag/v1.3.0-rc.1) (2019-07-03)
 =============================================================================================================
 [Full Changelog](https://github.com/matrix-org/matrix-react-sdk/compare/v1.2.2...v1.3.0-rc.1)