Add docker.io to namepsace the image source

Without this, on systems where multiple image sources are configured,
the user is prompted.  However, only docker.io appears to have the
images, so this should be set explicitly to prevent unnecessary user
hardship.

Author: FreedomBen

docker-compose.override.example.yml

@@ -43,7 +43,7 @@ services:
 #    ports: !reset []
 
   celery_flower:
-    image: wger/server:latest
+    image: docker.io/wger/server:latest
     command: /start-flower
     env_file:
       - ./config/prod.env

docker-compose.yml

@@ -7,7 +7,7 @@
 
 services:
   web:
-    image: wger/server:latest
+    image: docker.io/wger/server:latest
     depends_on:
       db:
         condition: service_healthy
@@ -29,7 +29,7 @@ services:
     restart: unless-stopped
 
   nginx:
-    image: nginx:stable
+    image: docker.io/nginx:stable
     depends_on:
       - web
     volumes:
@@ -47,7 +47,7 @@ services:
     restart: unless-stopped
 
   db:
-    image: postgres:15-alpine
+    image: docker.io/postgres:15-alpine
     environment:
       - POSTGRES_USER=wger
       - POSTGRES_PASSWORD=wger
@@ -66,7 +66,7 @@ services:
     restart: unless-stopped
 
   cache:
-    image: redis
+    image: docker.io/redis
     expose:
       - 6379
     volumes:
@@ -86,7 +86,7 @@ services:
     #mem_limit: 5gb
 
   celery_worker:
-    image: wger/server:latest
+    image: docker.io/wger/server:latest
     command: /start-worker
     env_file:
       - ./config/prod.env
@@ -103,7 +103,7 @@ services:
       start_period: 30s
 
   celery_beat:
-    image: wger/server:latest
+    image: docker.io/wger/server:latest
     command: /start-beat
     volumes:
       - celery-beat:/home/wger/beat/