BinaryPSO should return final best position instead of final swarm

[danielcorreia96]

Resolves #292

Description

The binary optimizer returns the entire final swarm instead of the final best position.

I think this happens because in the return stage of the optimize() function, we are copying self.swarm.best_pos which is an array (n_dimensions, particles), instead of the position of the best particle.

The expected behavior is implemented in local_best.py.

Related Issue

#292

Motivation and Context

How Has This Been Tested?

1. Ran tests locally
2. Example notebook (feature_selection)
3. Personal project

Screenshots (if appropriate):

See #292

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[ljvmiranda921]

Merged! Thank you for your contribution, @danielcorreia96 !