Add GitHub workflow for PHP version testing

Author: cammackmatthew

.github/workflows/tests.yml

@@ -0,0 +1,34 @@
+name: Tests
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+    branches:
+      - master
+
+jobs:
+  tests:
+    name: Run tests
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        php: [8.1, 8.2, 8.3]
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+
+      - name: Set up PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php }}
+          extensions: mbstring, sqlite3, pdo_sqlite, json, tokenizer, xml, curl, zip
+
+      - name: Install Composer dependencies
+        run: composer install --prefer-dist --no-progress --no-suggest
+
+      - name: Run tests
+        run: vendor/bin/phpunit