Update Rust crate handlebars to v6.4.3

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
handlebars	dependencies	patch	6.4.1 → 6.4.3

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Release Notes

sunng87/handlebars-rust (handlebars)

v6.4.3

Compare Source

• [Fixed] Panic when using whitespace omission (~) on an else if
  chain tag, e.g. {{~else if cond}}. The leading tilde is now handled
  consistently with {{~else}} [#​766]
• [Added] preserve_json_order feature flag that gates serde_json's
  preserve_order feature. Enabled by default to keep insertion-order key
  iteration; disable with default-features = false to restore alphabetical
  JSON object key ordering. [#​767]
• [Changed] Drop the pprof dev-dependency (and its inferno /
  quick-xml transitive deps) from benchmarks. This removes the vulnerable
  quick-xml 0.26 transitive dependency ([#​764], [#​765]); the upgrade was
  blocked upstream because pprof pins inferno 0.11. Benchmarks now use
  plain criterion without in-repo flamegraph generation.

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").

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