chore(deps): move off the yanked der 0.8.0

[sirahd]

cargo audit -D warnings fails on der 0.8.0, which has been yanked, so the Cargo Audit job is red on every PR (including #952, now main's HEAD). Bumps it to 0.8.2 — lockfile only, no manifest change. der arrives transitively via russh in git_xet's dev-dependencies.

cargo check -p git_xet --all-targets passes; local cargo audit can't verify against the registry proxy, so the Cargo Audit job here is the real check.

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Note

Low Risk
Lockfile-only transitive dependency bump with no application code changes.

Overview
Unblocks Cargo Audit by replacing the yanked der 0.8.0 with 0.8.2 in Cargo.lock only—no Cargo.toml changes. The crate is pulled in transitively (e.g. via russh in git_xet dev-dependencies), so this fixes the failing cargo audit -D warnings check that was red on CI.

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