Mock fix

[TedHammarlund]

Added functionality for calculating row distribution workload over threads. Now also used numcpu as default

[codecov-commenter]

Codecov Report

Attention: 27 lines in your changes are missing coverage. Please review.

Comparison is base (6bab2ea) 31.92% compared to head (14dffb6) 33.28%.
Report is 2 commits behind head on main.

Files	Patch %	Lines
src/mock.rs	38.63%	27 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #18      +/-   ##
==========================================
+ Coverage   31.92%   33.28%   +1.36%     
==========================================
  Files           5        5              
  Lines         686      712      +26     
==========================================
+ Hits          219      237      +18     
- Misses        467      475       +8     

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[wilhelmagren]

Resolve CI / Cargo format
run: cargo fmt in root of repo