Release 5.1.0

* Add support for custom Executor (threadpool) and HTTP Client
* Tokens module default/Four merge (single client)
* Fixes in CardCategory and CardType serialization

gradle.properties

@@ -1,5 +1,5 @@
 group=com.checkout
-version=5.0.0
+version=5.1.0
 
 maven2_url=https://oss.sonatype.org/service/local/staging/deploy/maven2/
 snapshot_url=https://oss.sonatype.org/content/repositories/snapshots/