using empty string instead of None to bind dualstack server

backend/app.py

@@ -227,7 +227,7 @@ if __name__ == '__main__':
     uvicorn.run(
         "app:app",
         # None allows to bind also on ipv6, and is selected if FIREGEX_HOST is any
-        host=None if FIREGEX_HOST == "any" else FIREGEX_HOST,
+        host="" if FIREGEX_HOST == "any" else FIREGEX_HOST,
         port=FIREGEX_PORT,
         reload=DEBUG and not NORELOAD,
         access_log=True,

run.py

@@ -309,7 +309,7 @@ def write_compose(skip_password = True):
                         "container_name": "firegex",
                         "build" if g.build else "image": "." if g.build else f"ghcr.io/pwnzer0tt1/firegex:{args.version}",
                         "ports": [
-                            f"{args.host}:{args.port}:{args.port}"
+                            f"{'' if args.host == 'any' else args.host+':'}{args.port}:{args.port}"
                         ],
                         "environment": [
                             f"PORT={args.port}",