Run tests in GitHub actions on PHP 8.1, 8.2, 8.3, 8.4

Author: pavog

.github/workflows/tests.yaml

@@ -12,7 +12,7 @@ jobs:
 
     strategy:
       matrix:
-        php-version: [ '8.1', '8.2', '8.3' ]
+        php-version: [ '8.1', '8.2', '8.3', '8.4' ]
 
     name: Run tests on PHP v${{ matrix.php-version }}