workflows: Move reposchutz workflow from Ubuntu 20.04 to 24.04

20.04 is EOL. "ubuntu-latest" is 24.04 now with a newer podman.

Cherry-picked from main commit fa65923.

Author: martinpitt

.github/workflows/reposchutz.yml

@@ -6,8 +6,7 @@ on:
 jobs:
   check:
     name: Protection checks
-    # 22.04's podman has issues with piping and causes tar errors
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     permissions:
       contents: read
       pull-requests: write