feat: Updated timing to more accurate one

[fg-mindee]

This PR simply replaces time.time() with time.perf_counter() which is much more recommended for latency benchmarks.

Any feedback is welcome!

[charlesmindee]

Thanks for that !

[codecov]

Codecov Report

Merging #769 (5960d3e) into main (8e7b0ee) will increase coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #769      +/-   ##
==========================================
+ Coverage   95.99%   96.01%   +0.02%     
==========================================
  Files         129      129              
  Lines        4818     4818              
==========================================
+ Hits         4625     4626       +1     
+ Misses        193      192       -1     

Flag	Coverage Δ
unittests	96.01% <ø> (+0.02%)	⬆️

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Impacted Files	Coverage Δ
doctr/transforms/modules/base.py	94.44% <0.00%> (ø)
doctr/models/builder.py	97.05% <0.00%> (+0.98%)	⬆️

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