fix: website check gh action

The GH action we use to daily check our website for issues did no
longer work as its implementation is incompatible to the latest
Ubuntu (24.04) default settings. Pins the Ubuntu version to 22.04 to fix
the issue for now.

.github/workflows/check-website.yml

@@ -6,7 +6,7 @@ on:
 
 jobs:
   check-webpage:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
 
     steps:
     - name: Checkout repository