chore: bump latest php version to 8.4

Author: JasonTheAdams

.github/workflows/unit-tests.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        php-version: ['7.4', '8.3']
+        php-version: ['7.4', '8.4']
 
     steps:
     - uses: actions/checkout@v4