Fake-useragent

**Changes:**
- Improve code quality standards using modern Python >=3.7 syntax
- Migrated to `pyproject.toml` build system format + syntax check
- Add additional classifiers to the toml file
- Improved `tox.ini` file
- Improved GitHub Actions job using pip cache
- And various small fixes

- Implement `browsers` argument, allowing you to override the browser names you want to use
- Fix browser listing of Internet Explorer and Edge
- Don't depend on w3schools.com anymore
- Clean-up data (temp) file format
- Update fallback cache server URL / use JSON Lines as file format
- Move to GitHub Actions instead of Travis
- Deployment done via GitHub Actions as well
- Using [`black`](https://pypi.org/project/black/) Python formatter in favour of Flake