Enable support for installing on NixOS

[kmjayadeep]

Description

Being a deterministic OS, NixOS doesn't support installing python packages through pip. In this PR I have added nix support using flake.nix. I had to update the poetry lock file as the build was failing.

Fyi: Syncall was added to nixos registry. But it doesn't seem to work as the optional dependencies are not installed.

Type of change

Please delete options that are not relevant.

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [x] This change requires a documentation update

How Has This Been Tested?

I started using this in my configuration, using the forked repo:

https://github.com/kmjayadeep/nixdots/blob/ceb205858722a0c32b5f86f7c6fa10cf1530e1bf/flake.nix#L27

Checklist:

• [x] My code follows the style guidelines of this project
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have made corresponding changes to the documentation
• [x] My changes generate no new warnings
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] Any dependent changes have been merged and published in downstream modules