docs: add changelog entry for v1.2.1 (#23)

Merge pull request #23 from d-Rickyy-b/dev

feat: implement utility functions for calculating system/unit code (#18)

Merge pull request #18 from d-Rickyy-b/dev

chore: implement GitHub build process for pypi

Merge pull request #12 from d-Rickyy-b/dev

FIX: Update maxDiff size for test

Also remove some print

Merge pull request #3 from d-Rickyy-b/dev

Add support for multiple gateways and devices

TASK: Add installation notes