Use actions instead of Travis (#75)

* Use actions instead of Travis

Author: barryvdh

.github/workflows/run-tests.yml

@@ -0,0 +1,39 @@
+name: Run tests
+
+on:
+  push:
+  schedule:
+  - cron: '0 0 * * *'
+
+jobs:
+  php-tests:
+    runs-on: ${{ matrix.os }}
+
+    strategy:
+      matrix:
+        php: [7.4, 7.3, 7.2, 7.1, 7.0]
+        dependency-version: [prefer-lowest, prefer-stable]
+        os: [ubuntu-latest, windows-latest]
+
+    name: PHP${{ matrix.php }} - ${{ matrix.os }} - ${{ matrix.dependency-version }}
+
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v1
+
+    - name: Setup PHP
+      uses: shivammathur/setup-php@v2
+      with:
+        php-version: ${{ matrix.php }}
+        extensions: mbstring
+
+    - name: Install dependencies
+      run: |
+        composer update --${{ matrix.dependency-version }} --prefer-dist --no-interaction --no-suggest
+
+    - name: Execute Unit Tests
+      run: vendor/bin/phpunit
+
+    - name: Check PSR-12 Codestyle
+      run: vendor/bin/phpcs --standard=psr12 src/
+      if: matrix.os == 'ubuntu-latest'