migrate From Travis CI to GitHub Actions

.github/workflows/python-package.yml

 # This workflow will install Python dependencies, run tests and lint with a variety of Python versions
 # For more information see: https://help.github.com/actions/language-and-framework-guides/using-python-with-github-actions
 
-name: Python package
+name: develop
 
 on:
   push:

.travis.yml

-# https://travis-ci.org/soimort/you-get
-language: python
-python:
-  - "3.4"
-  - "3.5"
-  - "3.6"
-  - "3.7"
-  - "3.8"
-  #- "nightly"  (flake8 not working in python 3.9 yet, module 'ast' has no attribute 'AugLoad')
-  - "pypy3"
-before_install:
-  - pip install flake8
-before_script:
-  - flake8 . --count --select=E9,F63,F72,F82 --show-source --statistics
-script: make test
-notifications:
-  webhooks:
-    urls:
-      - https://webhooks.gitter.im/e/43cd57826e88ed8f2152
-    on_success: change  # options: [always|never|change] default: always
-    on_failure: always  # options: [always|never|change] default: always
-    on_start: never     # options: [always|never|change] default: always

README.md

 # You-Get
 
+[![Build Status](https://github.com/soimort/you-get/workflows/develop/badge.svg)](https://github.com/soimort/you-get/actions)
 [![PyPI version](https://img.shields.io/pypi/v/you-get.svg)](https://pypi.python.org/pypi/you-get/)
-[![Build Status](https://travis-ci.org/soimort/you-get.svg)](https://travis-ci.org/soimort/you-get)
 [![Gitter](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/soimort/you-get?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 
 **NOTICE: Read [this](https://github.com/soimort/you-get/blob/develop/CONTRIBUTING.md) if you are looking for the conventional "Issues" tab.**