chore(docker-compose): replace hardcoded password with env variable

apps/shlink/config.json

@@ -16,7 +16,14 @@
   "author": "https://shlink.io/",
   "source": "https://github.com/shlinkio/shlink",
   "website": "https://shlink.io/",
-  "form_fields": [],
+  "form_fields": [
+    {
+      "type": "random",
+      "label": "Database password",
+      "min": 32,
+      "env_variable": "SHLINK_POSTGRES_PASSWORD"
+    }
+  ],
   "supported_architectures": [
     "arm64",
     "amd64"

apps/shlink/docker-compose.yml

@@ -10,7 +10,7 @@ services:
       - DB_HOST=shlink-db
       - DB_NAME=shlink
       - DB_USER=shlink
-      - DB_PASSWORD=shlink
+      - DB_PASSWORD=${SHLINK_POSTGRES_PASSWORD}
     ports:
       - ${APP_PORT}:8080
     restart: unless-stopped
@@ -53,6 +53,6 @@ services:
     volumes:
       - ${APP_DATA_DIR}/data/db:/var/lib/postgresql/data
     environment:
-      - POSTGRES_PASSWORD=shlink
+      - POSTGRES_PASSWORD=${SHLINK_POSTGRES_PASSWORD}
       - POSTGRES_USER=shlink
       - POSTGRES_DB=shlink