Remove travis, migrate to github actions

.travis.yml

-env:
-  global:
-    - CC_TEST_REPORTER_ID=8582900c285e4da0f253555b1bac1ba501bd6ff07850b0f227166b3cdac59ecc
-    
-language: python
-
-git:
-  depth: 3
-  
-notifications:
-  email: false
-
-python:
-  - 3.6
-  - 3.7
-  - 3.8
-  - 3.9
-
-install:
-  - pip install --upgrade pip setuptools wheel
-  - pip install --only-binary=numpy numpy
-  - pip install -r requirements.txt
-  - pip install 'coverage>=4.0,<4.4' --force-reinstall # Upstream bug: https://github.com/nedbat/coveragepy/issues/578
-  
-before_script:
-  - curl -L https://codeclimate.com/downloads/test-reporter/test-reporter-latest-linux-amd64 > ./cc-test-reporter
-  - chmod +x ./cc-test-reporter
-  - ./cc-test-reporter before-build
-  - python setup.py develop  # need to install to get version number
-  
-script: python ./test.py
-
-after_script:
-  - ./cc-test-reporter after-build --exit-code $TRAVIS_TEST_RESULT