Downgrade to docker-compose v3.7 so MZ can use it on ubuntu

Author: willcl-ark

src/warnet/warnet.py

@@ -246,7 +246,7 @@ def docker_compose_down(self):
     @bubble_exception_str
     def write_docker_compose(self, dns=True):
         compose = {
-            "version": "3.8",
+            "version": "3.7",
             "networks": {
                 self.docker_network: {
                     "name": self.docker_network,