[TASK] Update ubuntu images in gh workflows

Github is dropping support for old images. So we update to
the latest ubuntu lts images.

Author: mschwemer

.github/workflows/testing.yaml

@@ -10,7 +10,7 @@ on:
 jobs:
   php-lint:
     name: "PHP linter"
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-24.04
     steps:
       - name: "Checkout"
         uses: actions/checkout@v4
@@ -31,7 +31,7 @@ jobs:
           - 8.3
   typoscript-lint:
     name: "TypoScript linter"
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-24.04
     steps:
       - name: "Checkout"
         uses: actions/checkout@v4
@@ -42,7 +42,7 @@ jobs:
           config_file: ".project/tests/typoscript-lint.yml"
   php-cs-fixer:
     name: "PHP CS Fixer"
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-24.04
     needs: php-lint
     steps:
       - name: "Checkout"
@@ -57,7 +57,7 @@ jobs:
         run: "composer test:php:cs"
   phpstan:
     name: "PHPstan"
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-24.04
     needs: php-lint
     steps:
       - name: "Checkout"
@@ -72,7 +72,7 @@ jobs:
         run: "composer test:php:phpstan"
   unit-tests:
     name: "PHP Unit Tests"
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-24.04
     needs: php-lint
     steps:
       - name: Checkout