Update build process

[jagmoreira]

Context

While working on #177 I noticed that skelebot uses setup.y [...] test which has been deprecated.

Not only that, while reading through the latest documentation of setuptools I learned that it's not recommend to even have a setup.py anymore: https://setuptools.readthedocs.io/en/latest/userguide/index.html

Feature

Deprecated features should be removed from the build process and testing could also be separate from installation imo (this would have the added benefit of removing 2 dependencies for end-users: coverage and pytest).

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Acceptance Criteria

• No deprecated commands or keywords on build process
• Separate testing and installation dependencies