Add PHP 8.4 to CI matrix

Author: chr-hertel

.github/workflows/test.yml

@@ -9,7 +9,7 @@ jobs:
     strategy:
       fail-fast: true
       matrix:
-        php: [ 8.1, 8.2, 8.3 ]
+        php: [ 8.1, 8.2, 8.3, 8.4 ]
         dependency-version: [ prefer-lowest, prefer-stable ]
 
     name: Tests on PHP ${{ matrix.php }} - ${{ matrix.dependency-version }}
@@ -49,4 +49,4 @@ jobs:
         run: composer update --${{ matrix.dependency-version }} --no-interaction --prefer-dist
 
       - name: Run tests
-        run: composer test
+        run: composer test