added missed restart:always option for traefik service (#3600)

docker-compose.yml

@@ -68,6 +68,7 @@ services:
   traefik:
     image: traefik:v2.4
     container_name: traefik
+    restart: always
     command:
       - "--providers.docker.exposedByDefault=false"
       - "--providers.docker.network=cvat"
@@ -95,4 +96,4 @@ volumes:
   cvat_logs:
 
 networks:
-  cvat:
\ No newline at end of file
+  cvat: