Remove Travis as a CI platform (#6369)

It's currently causing weird unknown problems in React tests that run
successfully everywhere else, and by now all the tests that run on
Travis also run on CircleCI, so Travis is not needed anymore.
Signed-off-by: Julius Volz <julius.volz@gmail.com>

.circleci/config.yml

@@ -6,7 +6,7 @@ orbs:
   go: circleci/go@0.2.0
 
 executors:
-  # Whenever the Go version is updated here, .travis.yml and .promu.yml
+  # Whenever the Go version is updated here, .promu.yml
   # should also be updated.
   golang:
     docker:

.promu.yml

 go:
-    # Whenever the Go version is updated here, .travis.yml and
+    # Whenever the Go version is updated here,
     # .circle/config.yml should also be updated.
     version: 1.13
 repository:

.travis.yml

-language: go
-
-# Whenever the Go version is updated here, .circleci/config.yml and .promu.yml
-# should also be updated.
-go:
-- 1.13.x
-
-go_import_path: github.com/prometheus/prometheus
-
-# This ensures that the local cache is filled before running the CI.
-# travis_retry retries the command 3 times if it fails as we've experienced
-# random issues on Travis.
-before_install:
-- travis_retry make deps
-- . $HOME/.nvm/nvm.sh
-- nvm install stable
-- nvm use stable
-- if [[ "$TRAVIS_OS_NAME" == "windows" ]]; then choco install make; fi
-
-script:
-- make check_license style unused test lint
-- git diff --exit-code

README.md

@@ -102,7 +102,7 @@ For more information on building, running, and developing on the new React-based
 ## More information
 
   * The source code is periodically indexed: [Prometheus Core](https://godoc.org/github.com/prometheus/prometheus).
-  * You will find a Travis CI configuration in `.travis.yml`.
+  * You will find a CircleCI configuration in `.circleci/config.yml`.
   * See the [Community page](https://prometheus.io/community) for how to reach the Prometheus developers and users on various communication channels.
 
 ## Contributing
@@ -114,7 +114,6 @@ Refer to [CONTRIBUTING.md](https://github.com/prometheus/prometheus/blob/master/
 Apache License 2.0, see [LICENSE](https://github.com/prometheus/prometheus/blob/master/LICENSE).
 
 
-[travis]: https://travis-ci.org/prometheus/prometheus
 [hub]: https://hub.docker.com/r/prom/prometheus/
 [circleci]: https://circleci.com/gh/prometheus/prometheus
 [quay]: https://quay.io/repository/prometheus/prometheus