github: bump ubuntu runners to 24.04

20.04 is EOL soon.

Author: achilleas-k

.github/workflows/tests.yml

@@ -56,7 +56,7 @@ jobs:
 
   shellcheck:
     name: "🐚 Shellcheck"
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-24.04
     steps:
     - uses: actions/checkout@v4
       with: