add imap port to compose file

Signed-off-by: Felix Bartels <felix@host-consultants.de>

docker-compose.yml

@@ -359,6 +359,8 @@ services:
   kopano_gateway:
     image: ${docker_repo:-zokradonh}/kopano_core:${CORE_VERSION:-latest}
     container_name: kopano_gateway
+    ports:
+      - "143:143"
     volumes:
       - kopanossl/:/kopano/ssl
       - kopanosocket/:/run/kopano