fix docker-compose override

.gitignore

@@ -5,3 +5,4 @@ server
 sample*.drawio
 sample*.gliffy
 .DS_Store
+docker-compose.override.yml

docker-compose.yml

@@ -1,10 +1,8 @@
-version: "3.9"
-
 services:
   gliffy2drawio:
     build: .
     ports:
-      - "8080:8080"
+      - "${HOST_PORT:-8080}:8080"
     environment:
       - DRAWIO_BASE_URL=${DRAWIO_BASE_URL:-https://app.diagrams.net}
     restart: unless-stopped