Fix broker download path for Travis CI

Author: acogoluegnes

bin/before_build.sh

@@ -1,6 +1,6 @@
 #!/bin/sh
 
-wget https://github.com/rabbitmq/rabbitmq-server/releases/download/v3.7.8/rabbitmq-server-generic-unix-3.7.9.tar.xz
+wget https://github.com/rabbitmq/rabbitmq-server/releases/download/v3.7.9/rabbitmq-server-generic-unix-3.7.9.tar.xz
 tar xf rabbitmq-server-generic-unix-3.7.9.tar.xz
 mv rabbitmq_server-3.7.9 rabbitmq