Feat&Dev: Set up CI with GitHub actions

### Is your feature request related to a problem? Please describe.
For easy deploy and maintainability of the project and continuous delivery, we need to set up the CI flow. It will make the PR checking easier, enable testing and make the development and deployment much easier.

### Describe the solution you'd like
Set up the GitHub actions CI. Steps to set up:
1) linting (black formatted, flake check and isort)
2) setup the dev environment (Python and dependencies)
3) run tests -> we should set up them
4) make the code coverage report

### Describe alternatives you've considered
An alternative is to use some other CI tool like TravisCI, the possible problem is the limitation for free usage of Travis.
https://blog.travis-ci.com/2020-11-02-travis-ci-new-billing
### Additional context
N/A