Switch to Poetry

[danielgafni]

• Switch to Poetry dependencies manager
• Add docker image GPU support (FROM nvidia/cuda:11.1-base)
• Add optional "production" docker build without development dependencies (controllable with the DEPS=[development, production] build arg)
• Add optional docker build with a fix for nvidia 30xx GPUs (controllable with the NVIDIA_30XX=[true, false] build arg)
• Local Black pre-commit hook (benefits - fixed black version)
• CI fixes
• Required Python version changed 3.6 -> 3.7 (because of scikit-image incompatibility):

The current project's Python requirement (3.6.13) is not compatible with some of the required packages Python requirement:
    - scikit-image requires Python >=3.7, so it will not be satisfied for Python 3.6.13
  
  Because scikit-image (0.18.3) requires Python >=3.7
   and no versions of scikit-image match >0.18.3,<0.19.0, scikit-image is forbidden.
  So, because bindsnet depends on scikit-image (^0.18.3), version solving failed.

[danielgafni]

A few python files were changed but that's just Black formatting

[danielgafni]

@Hananel-Hazan should I also update CONTRIBUTING.md with poetry related instructions?

[Hananel-Hazan]

@danielgafni , Please do that

[Hananel-Hazan]

Thanks @danielgafni for the great work!