add github action workflow

.github/workflows/run-tests.yml

@@ -0,0 +1,39 @@
+name: "Run Tests"
+
+on: [push]
+
+jobs:
+  test:
+
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: true
+      matrix:
+        php: [7.2, 7.3, 7.4]
+        laravel: [5.8.*, 6.*]
+        dependency-version: [prefer-lowest, prefer-stable]
+
+    name: P${{ matrix.php }} - L${{ matrix.laravel }} - ${{ matrix.dependency-version }}
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v1
+
+      - name: Cache dependencies
+        uses: actions/cache@v1
+        with:
+          path: ~/.composer/cache/files
+          key: dependencies-laravel-${{ matrix.laravel }}-php-${{ matrix.php }}-composer-${{ hashFiles('composer.json') }}
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v1
+        with:
+          php-version: ${{ matrix.php }}
+          extensions: dom, curl, libxml, mbstring, zip, pcntl, pdo, sqlite, pdo_sqlite, bcmath, soap, intl, gd, exif, iconv, imagick
+          coverage: none
+
+      - name: Install dependencies
+        run: composer update --${{ matrix.dependency-version }} --prefer-dist --no-interaction --no-suggest
+
+      - name: Execute tests
+        run: vendor/bin/phpunit