ci: run Python 3.8 diagnostics on current runner

Author: Undertone0809

.github/workflows/dependency-refresh.yml

@@ -113,7 +113,7 @@ jobs:
 
   python38-compatibility:
     if: github.actor != 'github-actions[bot]'
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-24.04
     steps:
       - uses: actions/checkout@v4
         with: