Test with PHP 8.4

Author: firstred

.github/workflows/test.yaml

@@ -6,7 +6,7 @@ jobs:
         strategy:
             matrix:
                 operating-system: [ 'ubuntu-latest', 'windows-latest', 'macos-latest' ]
-                php-versions: [ '8.1', '8.2', '8.3' ]
+                php-versions: [ '8.1', '8.2', '8.3', '8.4' ]
         steps:
             -   name: Checkout repo
                 uses: actions/checkout@v2