Chore: Update PHP version matrix in CI workflow to include 8.4

Author: chikondikamwendo

.github/workflows/run-tests.yml

@@ -17,7 +17,7 @@ jobs:
             fail-fast: true
             matrix:
                 os: [ubuntu-latest, windows-latest, macos-latest]
-                php: [8.3]
+                php: [8.3, 8.4]
                 laravel: [11.*]
                 stability: [prefer-lowest, prefer-stable]
                 include: