chore(deps): pull in chacha20 0.10.2 and unbreak the deny job

[henry40408]

Closes #101.

The 7-day publish cooldown on chacha20 0.10.2 (published 2026-08-27) has cleared, so the temporary [advisories] ignore exception parked by #100 can go.

• cargo update -p chacha20 (0.10.0 -> 0.10.2)
• Drop the chacha20@0.10.0 ignore entry from deny.toml and revert the ignore doc comment now that the list is empty again

Also in here: event-listener 5.4.2

RUSTSEC-2026-0221 landed after #101 was filed and fails cargo deny on its own, so the deny job would have stayed red without it. event-listener <=5.4.1 unconditionally implements Send/Sync for StackSlot<'_, T>, letting a !Send tag set via Event::with_tag cross a thread boundary. We reach the crate only transitively via sqlx-core and never call Event::with_tag, but the advisory is a hard failure regardless. 5.4.2 was published 2026-07-27, well clear of the cooldown, and drops the concurrent-queue dependency.

Verification

$ cargo deny check
advisories ok, bans ok, licenses ok, sources ok

$ cargo clippy --all-targets -- -D warnings
Finished `dev` profile [unoptimized + debuginfo] target(s) in 1m 16s

$ cargo nextest run
Summary [8.747s] 241 tests run: 241 passed, 0 skipped

No test accompanies this change: it is a lockfile and cargo-deny config change with no behaviour change in lur itself, and the existing suite plus cargo deny check cover it.

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.20%. Comparing base (8859544) to head (be54f98).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #103   +/-   ##
=======================================
  Coverage   91.20%   91.20%           
=======================================
  Files          31       31           
  Lines        4468     4468           
=======================================
  Hits         4075     4075           
  Misses        393      393           

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