Pin zeroize for old Rust CI

[joostjager]

zeroize 1.9.0 uses Rust 2024 metadata, which Cargo 1.75 cannot parse. Pin it to 1.8.2 for older toolchains so the transaction sync HTTPS feature check keeps passing on the MSRV job.

[ldk-reviews-bot]

I've assigned @tankyleo as a reviewer!
I'll wait for their review and will help manage the review process.
Once they submit their review, I'll check if a second reviewer would be helpful.

[ldk-claude-review-bot]

This is a trivial, correct CI dependency pin that mirrors the existing hyper-rustls pattern directly above it (same -lt 85 threshold, same cargo update --precise form). The comment accurately describes the cause and the change is consistent with surrounding code. I verified there's no conflicting zeroize pin elsewhere.

No issues found.

[valentinewallace]

LGTM if CI is happy

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.93%. Comparing base (6ac2cf3) to head (a8a4767).
⚠️ Report is 5 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4745   +/-   ##
=======================================
  Coverage   86.92%   86.93%           
=======================================
  Files         161      161           
  Lines      111661   111669    +8     
  Branches   111661   111669    +8     
=======================================
+ Hits        97065    97079   +14     
+ Misses      12088    12082    -6     
  Partials     2508     2508           

Flag	Coverage Δ
fuzzing-fake-hashes	8.45% <ø> (-0.01%)	⬇️
fuzzing-real-hashes	32.41% <ø> (-0.01%)	⬇️
tests	86.26% <ø> (+<0.01%)	⬆️

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