ci: update runner to ubuntu 24

Author: marcoieni

.github/workflows/checks.yml

@@ -2,10 +2,10 @@ name: Correctness Checks
 on: [push, pull_request]
 jobs:
   Run-Markdown-Checks:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-24.04
     steps:
       - name: checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
       - name: Install Python dependencies
         uses: py-actions/py-dependency-install@v3
         with: