Use runner image ubuntu 24.04

Author: TomHAnderson

.github/workflows/continuous-integration.yml

@@ -13,7 +13,7 @@ on:
 jobs:
   phpunit:
     name: "PHPUnit"
-    runs-on: "ubuntu-20.04"
+    runs-on: "ubuntu-24.04"
 
     strategy:
       fail-fast: false