in cover_tree.rs i64::MIN - 1 causes overflow. FIXED.

[skywardfire1]

Checklist

• [ yes ] My branch is up-to-date with development branch.
• [ yes ] Everything works and tested on latest stable Rust.
• [ yes ] Coverage and Linting have been applied

Im about to implement predict_proba for kNN. Extensive tests show a bug in cover_tree.rs.

When d = 0 an attempt to do i64::MIN - 1 is performed.

So this PR is a fix of it.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 44.33%. Comparing base (70d8a0f) to head (8ead30c).
⚠️ Report is 11 commits behind head on development.

Files with missing lines	Patch %	Lines
src/algorithm/neighbour/cover_tree.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@               Coverage Diff               @@
##           development     #361      +/-   ##
===============================================
- Coverage        45.59%   44.33%   -1.27%     
===============================================
  Files               93       95       +2     
  Lines             8034     7999      -35     
===============================================
- Hits              3663     3546     -117     
- Misses            4371     4453      +82     

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[Mec-iS]

thanks. I don't understand why format check fails, please run check --all