Set legal hold on evidence

curl --request POST \
  --url https://api.fluxer.app/v1/admin/reports/{report_id}/legal-hold \
  --header 'Authorization: <api-key>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "expires_at": "<string>"
}
'

{
  "held": true
}