Description

Travis CI has been bought by a private investor and it got VERY slow.

This PR will remove Travis CI completely and migrate our CI to Github Actions. Additionally, effective cache policies have been set up which makes the builds even faster than they were (long time ago) on Travis CI.

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)
• This change requires a documentation update

Checklist:

• I have performed a self-review of my own code
• The documentation has been adjusted accordingly
• The changes generate no new warnings
• Tests have been added that prove the fix is effective or that the feature works
• The changes are documented in the changelog
• The Homeassistant plugin has been adjusted in case of new config options