[2.x] Switch to GitHub Actions CI. (#221)

[2.x] Switch to GitHub Actions CI.

.github/workflows/test.yml

@@ -0,0 +1,34 @@
+name: Tests
+on: [push, pull_request]
+env:
+  CI: true
+
+jobs:
+  run:
+    name: Node ${{ matrix.node }} on ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+
+    strategy:
+      fail-fast: false
+      matrix:
+        # switch to `8` when https://github.com/actions/setup-node/issues/27 is fixed
+        node: [6, 8.16.1, 10, 12]
+        os: [ubuntu-latest, windows-latest]
+
+    steps:
+      - name: Clone repository
+        uses: actions/checkout@v1
+
+      - name: Set Node.js version
+        uses: actions/setup-node@v1
+        with:
+          node-version: ${{ matrix.node }}
+
+      - run: node --version
+      - run: npm --version
+
+      - name: Install npm dependencies
+        run: npm install
+
+      - name: Run tests
+        run: npm test

README.md

@@ -3,8 +3,8 @@
 [PostCSS] plugin to inline local/remote images.
 
 [PostCSS]: https://github.com/postcss/postcss
-[ci-img]:  https://travis-ci.org/bezoerb/postcss-image-inliner.svg
-[ci]:      https://travis-ci.org/bezoerb/postcss-image-inliner
+[ci-img]:  https://github.com/bezoerb/inline-critical/workflows/Tests/badge.svg
+[ci]:      https://github.com/bezoerb/inline-critical/actions?workflow=Tests
 
 ```css
 .foo {