Add GitHub Actions CI (#394)

* Add GitHub Actions CI; remove broken TravisCI

* Remove old Greenkeeper badge

.github/workflows/ci.yml

@@ -0,0 +1,24 @@
+name: Node.js CI
+on:
+  push:
+    branches: master
+  pull_request:
+
+jobs:
+  test:
+    strategy:
+      matrix:
+        node: [10.x, 12.x, 14.x, 16.x]
+        os: [ubuntu-latest, windows-latest]
+    runs-on: ${{ matrix.os }}
+    steps:
+    - run: git config --global core.autocrlf input
+    - uses: actions/checkout@v2
+    - name: Use Node.js ${{ matrix.node }}
+      uses: actions/setup-node@v1
+      with:
+        node-version: ${{ matrix.node }}
+    - run: npm install
+    - run: npm run ci
+    - run: nyc report --reporter=text-lcov | coveralls
+      continue-on-error: true

README.md

@@ -1,6 +1,5 @@
 [![npm][npm]][npm-url]
 [![node][node]][node-url]
-[![Greenkeeper badge](https://badges.greenkeeper.io/postcss/postcss-cli.svg)](https://greenkeeper.io/)
 [![tests][tests]][tests-url]
 [![cover][cover]][cover-url]
 [![chat][chat]][chat-url]
@@ -142,8 +141,8 @@ module.exports = (ctx) => ({
 [npm-url]: https://npmjs.com/package/postcss-cli
 [node]: https://img.shields.io/node/v/postcss-cli.svg
 [node-url]: https://nodejs.org/
-[tests]: http://img.shields.io/travis/postcss/postcss-cli/master.svg
-[tests-url]: https://travis-ci.org/postcss/postcss-cli
+[tests]: https://img.shields.io/github/workflow/status/postcss/postcss-cli/Node.js%20CI/master
+[tests-url]: https://github.com/postcss/postcss-cli/actions?query=branch%3Amaster
 [cover]: https://img.shields.io/coveralls/postcss/postcss-cli/master.svg
 [cover-url]: https://coveralls.io/github/postcss/postcss-cli
 [chat]: https://img.shields.io/gitter/room/postcss/postcss.svg