Update ci.yml

Update CI to PHP 8.3+

Author: ralflang

.github/workflows/ci.yml

@@ -26,8 +26,8 @@ jobs:
     runs-on: ${{ matrix.operating-system }}
     strategy:
       matrix:
-        operating-system: ['ubuntu-20.04']
-        php-versions: ['7.4', '8.0', '8.1', 'latest']
+        operating-system: ['ubuntu-24.04']
+        php-versions: ['8.3', '8.4']
         phpunit-versions: ['latest', '9.5']
     steps:
     - name: Setup github ssh key