ci: bump ubuntu version for reusable_testing

This patch bumps the Ubuntu distro version up to 24.04 (noble) in the
aforementioned workflow, since the Ubuntu 20.04 (focal) image support
will be dropped soon in the GitHub actions.

See also: actions/runner-images#11101

Author: Buristan

.github/workflows/reusable_testing.yml

@@ -5,13 +5,13 @@ on:
     inputs:
       artifact_name:
         description: The name of the tarantool build artifact
-        default: ubuntu-focal
+        default: ubuntu-noble
         required: false
         type: string
 
 jobs:
   run_tests:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-24.04
     steps:
       - name: Clone the tarantool-c connector
         uses: actions/checkout@v4