chore(deps): bump brace-expansion to resolve security alert (#984)

Bumps the vulnerable `brace-expansion` transitive dependency in
`website/pnpm-lock.yaml` to resolve a high-severity Dependabot alert.

- `brace-expansion` 2.1.2 → 2.1.3 (high)

The 1.x (1.1.16) and 5.x (5.0.8) lines were already at patched versions.

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