Bump version to 0.54.1 and update jiter to 0.15

[adriangb]

Summary

• Bump version 0.54.0 → 0.54.1
• Update jiter 0.13.0 → 0.15.0
• log left at 0.4 (already resolves to the latest 0.4.x)

Build and full test suite pass locally against jiter 0.15.

Once merged, push the v0.54.1 tag to trigger the crates.io release.

Note: the previously mislabeled v0.54.1 tag (which pointed at the 0.54.0 bump commit and published 0.54.0) has been corrected to v0.54.0.

🤖 Generated with Claude Code

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.68%. Comparing base (1a4450c) to head (4823775).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #117   +/-   ##
=======================================
  Coverage   83.68%   83.68%           
=======================================
  Files          18       18           
  Lines        1557     1557           
  Branches     1557     1557           
=======================================
  Hits         1303     1303           
  Misses        176      176           
  Partials       78       78           

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