[WiP] CI: test upcoming PHP 8.4 release

Author: kleisauke

.github/workflows/ci.yml

@@ -15,6 +15,7 @@ jobs:
           - php: '8.1'
           - php: '8.2'
           - php: '8.3'
+          - php: '8.4'
 
     steps:
       - name: Setup PHP
@@ -25,14 +26,14 @@ jobs:
           coverage: none
 
       - name: Checkout code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Install vips
         run: sudo apt install -y libvips --no-install-recommends
 
       - name: Install composer dependencies
         run: |
-          composer update --prefer-dist --no-interaction --no-progress --no-ansi 
+          composer update --prefer-dist --no-interaction --no-progress --no-ansi
 
       - name: PHPUnit
         run: composer test