security(rsr-certifier): bump rustls-webpki 0.103.10 → 0.103.12

Closes Dependabot alerts #12 + #13 on hyperpolymath/standards:

- GHSA-xgp8-3hg3-c2mh — webpki: name constraints accepted for
  certificates asserting a wildcard name.
- GHSA-965h-392x-2mh5 — webpki: name constraints for URI names
  incorrectly accepted.

Both advisories fixed in 0.103.12. Transitive dep (not declared in
any Cargo.toml); bump applied via `cargo update -p rustls-webpki
--precise 0.103.12`. Cargo.lock-only change.

Note: rsr-certifier has pre-existing build errors (missing modules /
deps in engine crate) unrelated to this bump — see rsr-certifier's
own backlog.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: hyperpolymath