[0.1] Fix MSRV compatibility

[TheBlueMatt]

8a39057 broke MSRV for 0.1 which is still 1.63. We fix it here.

[ldk-reviews-bot]

I've assigned @valentinewallace 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]

No issues found.

The diff is identical to my prior review pass. The changes are straightforward MSRV CI dependency pins and a semantically-equivalent is_some_and(|key| ...) → map(|key| ...).unwrap_or(false) replacement (since Option::is_some_and requires Rust 1.70+, above the 0.1 MSRV of 1.63), plus removal of now-unused imports in offers_tests.rs and peer_handler.rs.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.54%. Comparing base (b6f3ad7) to head (5b72cd4).

Additional details and impacted files

@@           Coverage Diff           @@
##              0.1    #4737   +/-   ##
=======================================
  Coverage   84.54%   84.54%           
=======================================
  Files         137      137           
  Lines       77617    77617           
  Branches    77617    77617           
=======================================
  Hits        65625    65625           
+ Misses       9949     9944    -5     
- Partials     2043     2048    +5     

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[tnull]

CI is failing.

[valentinewallace]

CI still failing

[TheBlueMatt]

I believe this is correct now. CI is now dependent on itself (its failing to build the release 0.1.10 lightning crate). rustfmt/linting/fuzz/build-tx-sync are legit-broken, but those aren't required to fix bindings.

[valentinewallace]

Should we go ahead and fix those checks? Otherwise, we're committing to those checks failing on 0.1, etc branches moving forward?

[TheBlueMatt]

Both linting and rustfmt have been failing for a while, in the lint case because it targets rustc stable and thus is a moving target. I believe I've fixed the others (except the one that depends on 0.1 itself).