curl --request POST \
  --url https://service.uat-keys.coincover.com/v1/partner/secure/file \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: multipart/form-data' \
  --form 'public_key=<string>' \
  --form file='@example-file' \
  --form 'metadata={
  "description": "<string>",
  "content_type": "<string>",
  "original_filename": "<string>"
}'

{
  "backup_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "backup_type": "file",
  "metadata": {}
}