Add pypdf layout whitespace fix commit reference

[cookesan]

Adds pypdf layout whitespace fix commit reference to GHSA-cj93-chg6-vgv8.

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/2026/06/GHSA-cj93-chg6-vgv8/GHSA-cj93-chg6-vgv8.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]

Rechecked this reference-only PR while keeping the open Advisory Database queue current.

• The patch adds the pypdf layout whitespace fix commit reference and normalizes the file's trailing newline; it does not change affected ranges, package metadata, or severity.
• The commit resolves to 9d2747057c4afc06ccc0fc6244a3915ba6ea6f0b.
• The commit subject matches the advisory context: SEC: Avoid excessive whitespace in layout mode text extraction (#3790).

No advisory data fields are changed.