ASF infra restricts GitHub Actions to a curated allowlist. The Build
workflow added in apache#15 used dtolnay/rust-toolchain and Swatinem/rust-cache,
both of which fail the policy check and cause the workflow to abort with
a startup_failure before any step runs.
Drop the rust-toolchain action — ubuntu-latest runners already ship with
rustup, so a plain run step that refreshes and defaults to stable
covers the same ground. Swap the cargo cache to actions/cache@v4 keyed
on native/Cargo.lock and pointing at the cargo registry, git, and the
native target directory.
Which issue does this PR close?
Follow-up to #15.
Rationale for this change
The Build workflow added in #15 fails immediately on every run with startup_failure:
ASF infra restricts GitHub Actions to a curated allowlist (mostly actions/* plus a small set of approved third parties). Both dtolnay/rust-toolchain and Swatinem/rust-cache fall outside that list, so the workflow aborts before any step runs and main currently has no working CI.
What changes are included in this PR?
How are these changes tested?
Verified that the previous run on main (commit 058840a) failed with startup_failure due to the disallowed action. CI on this PR will exercise the replacement steps end-to-end before merge.