replace travis with github actions

Author: Joel Butcher

.github/workflows/tests.yml

@@ -0,0 +1,36 @@
+name: tests
+
+on:
+  push:
+  pull_request:
+  schedule:
+    - cron: '0 0 * * *'
+
+jobs:
+  tests:
+
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: true
+      matrix:
+        php: [7.3, 7.4, 8.0]
+
+    name: PHP ${{ matrix.php }}
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php }}
+          extensions: dom, curl
+          tools: composer:v2
+          coverage: none
+
+      - name: Install dependencies
+        run: composer update --prefer-dist --no-interaction --no-progress
+
+      - name: Execute tests
+        run: vendor/bin/phpunit --verbose