add docker volume for stalwart logs

docker-compose.yml

@@ -30,6 +30,7 @@ services:
     volumes:
       - stalwart-etc:/etc/stalwart
       - stalwart-data:/var/lib/stalwart
+      - stalwart-logs:/var/log/stalwart
     networks:
       - services
 
@@ -74,6 +75,7 @@ volumes:
   caddy-config:
   stalwart-etc:
   stalwart-data:
+  stalwart-logs:
   bulwark-settings:
   bulwark-config:
   bulwark-state: