Update Rust crate handlebars to v6.4.2

[kindabot]

This PR contains the following updates:

Package	Type	Update	Change
handlebars	dependencies	patch	6.4.1 → 6.4.2

---

Release Notes

sunng87/handlebars-rust (handlebars)

v6.4.2

Compare Source

• [Fixed] Access to local variables like @key, @index, etc. in #with and
  partial block [#​758]
• [Fixed] Preserve ordering when iterating an array context inside a partial
  that receives hash parameters [#​760]
• [Changed] Enable serde_json preserve_order feature. JSON objects are now
  iterated in insertion order (matching Handlebars.js semantics) instead of
  alphabetical key order. This fixes index-key ordering for array contexts
  converted into objects by partial hash parameters (e.g. "10" no longer
  sorts before "2").

---

Configuration

📅 Schedule: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

---

• If you want to rebase/retry this PR, check this box

---

This PR has been generated by Renovate Bot.