Add CORS sampler

[AldoGl]

This PR adds the CORS sampler to Black-it.

Reference to the CORS sampler:
Regis, Rommel G., and Christine A. Shoemaker. "Constrained global optimization of expensive black box functions using radial basis functions." Journal of Global optimization 31.1 (2005): 153-171.

The PR also changes the name of black-it.utils.assert_ to black-it.utils._assert

[codecov-commenter]

Codecov Report

Merging #28 (5abb3c2) into main (fedece7) will decrease coverage by 8.03%.
The diff coverage is 41.37%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #28      +/-   ##
==========================================
- Coverage   97.72%   89.68%   -8.04%     
==========================================
  Files          23       25       +2     
  Lines        1231     1416     +185     
==========================================
+ Hits         1203     1270      +67     
- Misses         28      146     +118     

Impacted Files	Coverage Δ
black_it/search_space.py	100.00% <ø> (ø)
black_it/samplers/cors.py	21.64% <21.64%> (ø)
black_it/samplers/knysh_korkolis.py	43.24% <43.24%> (ø)
black_it/samplers/particle_swarm.py	92.22% <66.66%> (ø)
black_it/calibrator.py	97.48% <100.00%> (ø)
black_it/loss_functions/base.py	100.00% <100.00%> (ø)
black_it/loss_functions/fourier.py	100.00% <100.00%> (ø)
black_it/loss_functions/gsl_div.py	100.00% <100.00%> (ø)
black_it/samplers/best_batch.py	100.00% <100.00%> (ø)
black_it/samplers/random_forest.py	100.00% <100.00%> (ø)

[marcofavoritobi]

LGTM