Add Github Actions

I did not see any inspections. This will add PHPUnit inspections for PHP versions 7.1, 7.2, 7.3, 7.4 and 8.0

.github/workflows/pull_request.yml

@@ -0,0 +1,23 @@
+name: Inspections
+
+on: [pull_request]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        php-versions: ['7.1', '7.2', '7.3', '7.4', '8.0']
+    name: PHP ${{ matrix.php-versions }}
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php-versions }}
+          coverage: xdebug
+      - name: Install dependencies
+        run: composer install --prefer-dist --no-progress --no-suggest
+      - name: Unit tests
+        run: ./vendor/bin/phpunit