Explore other CI than Travis

[MaciejWiczk]

It would be nice to be able to run CI on various python versions (>=3.6) and on different OS matrix. Travis can do that, but it's not so easy to gather build artfiacts, such as robot logs and reports, that might be useful when creating new feature. Github Actions seems like nice choice. Here are some links to materials I found useful:

• workflow with postgres
• workflow with Xvfb, for selenium
• workflow with persistance artifacts, to store robot files