More Wayland support

[HorlogeSkynet]

Reason and / or context

See #151.

How has this been tested ?

Locally + unit tests.

Types of changes :

• Bug fix (non-breaking change which fixes an issue)
• Typo / style fix (non-breaking change which improves readability)
• New feature (non-breaking change which adds functionality)
• [Breaking change (fix or feature that would cause existing functionality to change)

Checklist :

• [IF NEEDED] I have updated the README.md file accordingly ;
• [IF NEEDED] I have updated the test cases (which pass) accordingly ;
• [IF BREAKING] This pull request targets next Archey version branch ;
• My changes looks good ;
• I agree that my code may be modified in the future ;
• My code follows the code style of this project (PEP8).

[HorlogeSkynet]

1. @Nagefire sorry for the delay, tests were failing against Python 3.6 ...
2. @ingrinder sorry (too !) for the future required conflicts for other ongoing work... 😇

Thanks, bye 👋

[ingrinder]

In my calendar to review around 27th May if you can wait 'til then! Planning to set up a VM with all of the supported DEs/WMs to double-check for any regressions (unless you've already done so!)