chore: fix clippy warnings from Rust release 1.69

[morenol]

Fixed running cargo clippy --fix

[codecov-commenter]

Codecov Report

Merging #263 (683cc03) into development (9cd7348) will decrease coverage by 0.02%.
The diff coverage is 28.57%.

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@@               Coverage Diff               @@
##           development     #263      +/-   ##
===============================================
- Coverage        45.38%   45.37%   -0.02%     
===============================================
  Files               85       85              
  Lines             7231     7231              
===============================================
- Hits              3282     3281       -1     
- Misses            3949     3950       +1     

Impacted Files	Coverage Δ
src/model_selection/kfold.rs	59.52% <ø> (ø)
src/readers/csv.rs	56.36% <0.00%> (ø)
src/linalg/basic/matrix.rs	48.83% <33.33%> (ø)

... and 10 files with indirect coverage changes

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[morenol]

@Mec-iS Please review and merge if you think that it is ok