CHANGELOG.md in stellar-base-0.12.0 vs CHANGELOG.md in stellar-base-0.13.0

@@ -4,10 +4,18 @@
 file.  This project adheres to [Semantic Versioning](http://semver.org/).
 
 As this project is pre 1.0, breaking changes may happen for minor version
 bumps.  A breaking change will get clearly notified in this log.
 
-## [unreleased](https://github.com/stellar/ruby-stellar-base/compare/v0.12.0...master)
+## [unreleased](https://github.com/stellar/ruby-stellar-base/compare/v0.13.0...master)
+
+## [0.13.0](https://github.com/stellar/ruby-stellar-base/compare/v0.12.0...v0.13.0)
+
+### Changed
+- Update XDR definitions for stellar-core 0.9.1 support
+
+### Added
+- Added `#signer_key` helper to `KeyPair`
 
 ## [0.12.0](https://github.com/stellar/ruby-stellar-base/compare/v0.11.0...v0.12.0)
 
 ### Changed
 - Avoid modifying $LOAD_PATH to fix load order issues