chore: bump version to 5.1.0-SNAPSHOT

gradle.properties

@@ -1,4 +1,4 @@
-projectVersion=5.0.3-SNAPSHOT
+projectVersion=5.1.0-SNAPSHOT
 
 # This prevents the Grails Gradle Plugin from unnecessarily excluding slf4j-simple in the generated POMs
 # https://github.com/grails/grails-gradle-plugin/issues/222
@@ -9,7 +9,7 @@ authors=Graeme Rocher
 projectDesc=Grails Async Libraries
 projectUrl=https://github.com/grails/grails-async
 githubSlug=grails/grails-async
-githubBranch=5.0.x
+githubBranch=5.1.x
 developers=Graeme Rocher, Mattias Reichel
 
 #gpars docs is currently not available with https
@@ -19,4 +19,4 @@ rxjava2docs=https://reactivex.io/RxJava/2.x/javadoc
 
 org.gradle.caching=true
 org.gradle.daemon=true
-org.gradle.parallel=true
+org.gradle.parallel=true