Fix CI to use Pest instead of PHPUnit, add PHP 8.4 to matrix

Author: jszobody

.github/workflows/tests.yml

@@ -12,7 +12,7 @@ jobs:
 
     strategy:
       matrix:
-        php: ['8.3', '8.5']
+        php: ['8.3', '8.4', '8.5']
 
     name: PHP ${{ matrix.php }}
 
@@ -30,4 +30,4 @@ jobs:
         run: composer install --no-interaction --prefer-dist
 
       - name: Run tests
-        run: vendor/bin/phpunit
+        run: vendor/bin/pest