amqp_postgres test: use rabbitmq 3.7.7  (#1400)
amqp_postgres test: use rabbitmq 3.7.7  (#1400)

* amqp_postgres test: use rabbitmq 3.7.7

* Docker version too

cloudify-cosmo/cloudify-manager,cloudify-cosmo/cloudify-manager,cloudify-cosmo/cloudify-manager