CI: add PHP 8.4

Author: dktapps

.github/workflows/ci.yml

@@ -8,7 +8,7 @@ jobs:
     if: "!contains(github.event.head_commit.message, '[ci skip]')"
     strategy:
       matrix:
-        php: ['8.1', '8.2', '8.3']
+        php: ['8.1', '8.2', '8.3', '8.4']
     name: PHP ${{ matrix.php }}
     steps:
     - uses: actions/checkout@v4