Move the pin to Rust 1.98 #35

The compiler this binding builds with is not chosen here. toolchains.toml in tamnd/zu holds one version for the nine repositories that build Rust, and rust-toolchain.toml here is a copy of that row. tamnd/zu#515 moves it to 1.98.0, so this moves with it.

Four sites: the toolchain channel, rust-version in Cargo.toml, and the rust-toolchain input maturin takes in wheels.yml and install.yml, which are named rather than left to the toolchain file because the manylinux and musllinux containers do not read it.

The dependencies are all on their newest series as of 2026-08-21: pyo3 0.29.2, numpy 0.29.0, arrow 59.2.0.