Remove Travis CI config (#44443)

https://blog.travis-ci.com/2020-11-02-travis-ci-new-billing
https://docs.travis-ci.com/user/migrate/open-source-repository-migration/#frequently-asked-questions

.travis.yml

-dist: focal
-addons:
-  apt:
-    packages:
-      - ffmpeg
-      - libudev-dev
-      - libavformat-dev
-      - libavcodec-dev
-      - libavdevice-dev
-      - libavutil-dev
-      - libswscale-dev
-      - libswresample-dev
-      - libavfilter-dev
-
-python:
-  - "3.7.1"
-  - "3.8"
-
-env:
-  - TOX_ARGS="-- --test-group-count 4 --test-group 1"
-  - TOX_ARGS="-- --test-group-count 4 --test-group 2"
-  - TOX_ARGS="-- --test-group-count 4 --test-group 3"
-  - TOX_ARGS="-- --test-group-count 4 --test-group 4"
-
-jobs:
-  fast_finish: true
-  include:
-    - python: "3.7.1"
-      env: TOXENV=lint
-    - python: "3.7.1"
-      # PYLINT_ARGS=--jobs=0 disabled for now: https://github.com/PyCQA/pylint/issues/3584
-      env: TOXENV=pylint TRAVIS_WAIT=30
-    - python: "3.7.1"
-      env: TOXENV=typing
-
-cache:
-  pip: true
-  directories:
-    - $HOME/.cache/pre-commit
-install: pip install -U tox tox-travis
-language: python
-script: ${TRAVIS_WAIT:+travis_wait $TRAVIS_WAIT} tox -vv --develop ${TOX_ARGS-}

docs/source/conf.py

@@ -207,7 +207,6 @@ html_theme_options = {
     "github_repo": PROJECT_GITHUB_REPOSITORY,
     "github_type": "star",
     "github_banner": True,
-    "travis_button": True,
     "touch_icon": "logo-apple.png",
     # 'fixed_sidebar': True, # Re-enable when we have more content
 }