ci: Delete travis settings as they no longer support OSS

Very sad indeed

.travis.yml

@@ -1,60 +0,0 @@
-# YAML anchors need to appear first.
-# Keys starting with an underscore are the custom ones, refer to
-# https://docs.travis-ci.com/user/build-config-yaml#private-keys-as-yaml-anchors-and-aliases-and-external-tooling
-
-_native_job: &native_job
-  script: |
-    test/run
-
-language: shell
-
-os: linux
-
-dist: xenial
-
-cache:
-  directories:
-  - "${HOME}/.cache/pip"
-  - "${HOME}/.cache/pre-commit"
-  - "${HOME}/.pre-commit-venv"
-  - "${HOME}/bin"
-  - /usr/lib/python3.8
-
-jobs:
-  include:
-  - language: python
-    python: 3.8
-    name: docs
-    dist: bionic
-    install:
-      pip3 install -r docs/requirements.txt;
-    script:
-      sphinx-build -W -b html docs docs/_build/html;
-
-  - language: go
-    go: "1.14"
-    name: pre-commit lint
-    dist: bionic
-    sudo: required
-    before_script:
-      GO111MODULE=on go get mvdan.cc/sh/v3/cmd/shfmt;
-      curl https://pre-commit.com/install-local.py | python3 -
-    script:
-      ./lint_clean_files.sh;
-
-  - <<: *native_job
-    name: Ubuntu 16.04
-
-  - <<: *native_job
-    name: Ubuntu 18.04
-    dist: bionic
-
-  - <<: *native_job
-    name: MacOS xcode9.4
-    os: osx
-    osx_image: xcode9.4 # Default xcode on Travis.
-
-  - <<: *native_job
-    name: MacOS xcode11.5
-    os: osx
-    osx_image: xcode11.5 # Latest xcode on Travis.