Merge branch 'traefik-v2' into 'master'

Migrate to Traefik v2

See merge request picasoft/projets/dockerfiles!53

pica-db-backup/docker-compose.yml

@@ -6,12 +6,9 @@ networks:
   etherpad_week:
     name: "etherpad_week"
   plume:
-    name: plume
+    name: "plume"
   wekan:
     name: "wekan"
-  docker_default:
-    external: true
-    name: "docker_default"
 
 services:
   db-backup:
@@ -24,7 +21,6 @@ services:
     env_file:
       - ./secrets/db.secrets
     networks:
-      - docker_default
       - etherpad_main
       - etherpad_week
       - plume