Fix service dependency name for postgres in Docker Compose configuration

opengist/compose.yaml

@@ -3,7 +3,7 @@ services:
     container_name: opengist
     image: ghcr.io/thomiceli/opengist:latest
     depends_on:
-      - serviceName: postgres
+      - postgres
     restart: unless-stopped
     environment:
       OG_GITHUB_CLIENT_KEY: ${OG_GITHUB_CLIENT_KEY}