fix(args): add gateway param & update tests

[tchapacan]

Description

Purpose of this PR is to add an optional arg to the cli, the gateway ip address of the livebox to be used. In case some users have a custom gateway (different than 192.168.1.1 default value), then an optional custom one can be supplied as args.

Fixing and aligning semver as well

Fix: #4

Type of change

• 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 not work as expected)
• Documentation update
• Test update
• Dependencies update

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes