Unsafe media served inline on download endpoints in matrix-media-repo

matrix-media-repo is a highly customizable multi-domain media repository for the Matrix chat ecosystem. In affected versions an attacker could upload a malicious piece of media to the media repo, which would then be served with `Content-Disposition: inline` upon download. This vulnerability could be leveraged to execute scripts embedded in SVG content. Commits `77ec235` and `bf8abdd` fix the issue and are included in the 1.3.0 release. Operators should upgrade to v1.3.0 as soon as possible. Operators unable to upgrade should override the `Content-Disposition` header returned by matrix-media-repo as a workaround.