[pre-commit.ci] auto fixes from pre-commit.com hooks

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src/backend/app/main.py

@@ -25,7 +25,7 @@
 from fastapi import FastAPI, Request
 from fastapi.exceptions import RequestValidationError
 from fastapi.middleware.cors import CORSMiddleware
-from fastapi.responses import FileResponse, HTMLResponse, JSONResponse, RedirectResponse
+from fastapi.responses import HTMLResponse, JSONResponse, RedirectResponse
 from loguru import logger as log
 from osm_fieldwork.xlsforms import xlsforms_path