Add PHP 8.4 in GitHub test workflow (#16)

* Add PHP 8.4 in GitHub test workflow
* Update github workflows actions

.github/workflows/build.yml

@@ -7,17 +7,17 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        php: ['8.1', '8.2', '8.3']
+        php: ['8.1', '8.2', '8.3', '8.4']
     name: Testing on PHP ${{ matrix.php }}
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
 
       - name: Setup PHP
         uses: shivammathur/setup-php@v2
         with:
           php-version: ${{ matrix.php }}
-          extensions: mbstring,bcmath
+          extensions: mbstring, bcmath, gd
           tools: composer
 
       - name: Install PHP dependencies