Bump HOP Version to 1.3.1.RELEASE

Fixes a content-type problem when running with a 3.7 broker.

Author: garyrussell

build.gradle

@@ -92,7 +92,7 @@ subprojects { subproject ->
 		logbackVersion = '1.2.3'
 		mockitoVersion = '2.11.0'
 		rabbitmqVersion = project.hasProperty('rabbitmqVersion') ? project.rabbitmqVersion : '5.0.0'
-		rabbitmqHttpClientVersion = '1.3.0.RELEASE'
+		rabbitmqHttpClientVersion = '1.3.1.RELEASE'
 		slf4jVersion = "1.7.25"
 
 		springVersion = project.hasProperty('springVersion') ? project.springVersion : '5.0.2.RELEASE'