v0.6.4

release: v0.6.4

Rust: codepage 0.1.3 (opens .xls files using code pages 10007 and
21010), encoding_rs 0.8.42, flate2 1.1.10 and transitive updates.
flate2 is now a direct dependency with runtime_detection enabled, since
zip disables flate2's defaults and 1.1.10 moved zlib-rs SIMD detection
behind that feature.

Elixir: tested against rustler_precompiled 0.10.0 and decimal 3.2.0;
dev/test dependency updates; drop stale inflex and toml lock entries;
mix format after the dialyxir removal left a trailing comma.

Parse output for every fixture in test/files is identical before and
after.