feat: use explicite image hub URL in compose.yml (#89)

This makes it work with podman in addition to docker.

Author: m4tx

compose.yml

@@ -1,6 +1,6 @@
 services:
   mariadb:
-    image: mariadb:11
+    image: docker.io/mariadb:11
     container_name: flareon-mariadb
     environment:
       MARIADB_DATABASE: mysql
@@ -11,7 +11,7 @@ services:
       - "3306:3306"
 
   postgres:
-    image: postgres:17-alpine
+    image: docker.io/postgres:17-alpine
     container_name: flareon-postgres
     environment:
       POSTGRES_USER: flareon