BE: devices.csv import from file did nt work becasue of too strict validation

Signed-off-by: jokob-sk <jokob.sk@gmail.com>

server/api_server/api_server_start.py

@@ -728,7 +728,7 @@ def api_export_devices(format=None, payload=None):
     operation_id="import_devices",
     summary="Import Devices",
     description="Import devices from CSV or JSON content.",
-    request_model=DeviceImportRequest,
+    request_model=None,
     response_model=DeviceImportResponse,
     tags=["devices"],
     auth_callable=is_authorized,