IONOS(ci): Add cancel-in-progress to concurrency configuration

Enable automatic cancellation of in-progress workflow runs when new
commits are pushed to the same branch or pull request. This prevents
redundant builds and saves CI resources.

Signed-off-by: Misha M.-Kupriyanov <kupriyanov@strato.de>

Author: printminion-co

.github/workflows/build-artifact.yml

@@ -52,7 +52,7 @@ on:
 concurrency:
   group: >-
     ${{ github.workflow }}-${{
-      github.event.pull_request.number ||
+      github.event_name == 'pull_request' && format('pr-{0}', github.event.pull_request.number) ||
       github.ref == 'refs/heads/ionos-dev' && github.run_id ||
       github.ref
     }}