Add support for PHP 8.3 tests (#18)

Author: nickbeen

.github/workflows/run-tests.yml

@@ -9,7 +9,7 @@ jobs:
         strategy:
             fail-fast: false
             matrix:
-                php: [8.2, 8.1, 8.0]
+                php: [8.3, 8.2, 8.1, 8.0]
                 os: [ubuntu-latest, windows-latest]
 
         name: PHP ${{ matrix.php }} - ${{ matrix.os }}