PR workflow: report deployment failure

[bernt-matthias]

I have tested this successfully with

• the standard merge and
• squash merge

Note, rebase merge does not work .. so we would need to disable this in the settings. This might be a limitation of the action used to get the PR number, but I guess its difficult / impossible because SHAs don't match to the SHAs of the commits in the PR.

FOR CONTRIBUTOR:

• - I have read the CONTRIBUTING.md document and this tool is appropriate for the tools-iuc repo.
• - License permits unrestricted use (educational + commercial)
• - This PR adds a new tool or tool collection
• - This PR updates an existing tool or tool collection
• - This PR does something else (explain below)

[bernt-matthias]

Thanks @bgruening .. I disabled the rebase merge option in the repo settings.