Bump version of Docker image. Update the stack file.

Signed-off-by: Roberto Rosario <roberto.rosario.gonzalez@gmail.com>

docker/stack.yml

@@ -1,5 +1,11 @@
 version: '3.1'
 
+volumes:
+    app:
+        driver: local
+    db:
+        driver: local
+
 services:
 
   db:
@@ -11,14 +17,16 @@ services:
       POSTGRES_USER: mayan
 
   app:
-    image: registry.gitlab.com/mayan-edms/mayan-edms
+    image: registry.gitlab.com/mayan-edms/mayan-edms:v3-0b3
     restart: always
     ports:
       - 8000:8000
     environment:
-      MAYAN_DATABASE_DRIVER: django.db.backends.postgres
+      MAYAN_DATABASE_ENGINE: django.db.backends.postgresql
       MAYAN_DATABASE_HOST: db
       MAYAN_DATABASE_NAME: mayan
       MAYAN_DATABASE_PASSWORD: mayan-password
       MAYAN_DATABASE_USER: mayan
+    volumes:
+      - app:/var/lib/mayan
 

docker/version

@@ -1 +1 @@
-3.0b1
+3.0b3