Added GitHub workflow

.github/workflows/tests.yml

@@ -0,0 +1,38 @@
+name: Tests
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  tests:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        php-version:
+          - "8.1"
+          - "8.3"
+
+    steps:
+    - uses: "actions/checkout@v3"
+    - uses: "shivammathur/setup-php@v2"
+      with:
+        php-version: ${{ matrix.php-version }}
+
+    - name: Validate composer.json and composer.lock
+      run: composer validate --strict
+
+    - name: Cache Composer packages
+      id: composer-cache
+      uses: actions/cache@v3
+      with:
+        path: vendor
+        key: php-${{ matrix.php-version }}-${{ hashFiles('**/composer.json') }}
+
+    - name: Install Composer dependencies
+      run: composer install --prefer-dist --no-progress
+
+    - name: Run test suite
+      run: composer run-script test