Snipe-IT's S3 signature image retrieval lacks authorization before temporary URL

Snipe-IT is an IT asset/license management system. Prior to version 8.6.1, Snipe-IT S3 signature image retrieval lacks authorization before temporary URL. On S3-backed deployments, authenticated users who know a signature filename can obtain a 5-minute signed S3 URL because the S3 branch returns before the `authorize()` call used by the local-file branch. Version 8.6.1 contains a patch.