Update changelog

Author: Ivan Stanković

CHANGELOG.md

@@ -5,6 +5,11 @@ Documents changes that result in:
 - API changes in the package (externally used constants, externally used utilities and scripts)
 - important bug fixes between releases
 
+## [0.38.0]
+- [#1462](https://github.com/raiden-network/raiden-contracts/pull/1462) TokenNetwork: allow updating channel state anytime before a channel is settled
+- [#1464](https://github.com/raiden-network/raiden-contracts/pull/1464) Use RDN as default token for service payments
+
+## [0.37.6]
 - [#1456](https://github.com/raiden-network/raiden-contracts/pull/1456) Add Python 3.9 support
 
 ## [0.37.5]