Add Gitea attachment deletion fix references

[cookesan]

Adds Gitea attachment deletion fix references to GHSA-hgr3-x44x-33hx.

Audit refresh, July 8, 2026:

• Confirmed the live PR is open, ready for review, merge-clean, and the visible advisory check is green.
• Rechecked the merge-base diff: exactly one advisory JSON file changes (advisories/github-reviewed/2026/01/GHSA-hgr3-x44x-33hx/GHSA-hgr3-x44x-33hx.json), JSON parses, git diff --check passes, and the exact-head worktree is clean.
• Revalidated the added public references in the diff; all resolve through their source site or registry.

[cookesan]

Maintainer audit: this only expands the reference set for the Gitea attachment deletion advisory. go-gitea/gitea#36320 merged to fbea2c68e8df11cfa94e8ead913b79946780ed30, the v1.25 backport #36355 merged to 11891c2dacfce3d5f483e8c4685097d8a5bb9184, the v1.25.4 release and Go module record resolve, and CVE-2026-20736 is present in NVD. The advisory JSON parses, the committed diff passes git diff --check, the PR is merge-clean, and advisory processing is successful. No package, affected range, severity, or database metadata is changed.