[7.6.z] Wrong version of Galleon dependency for server config migration tests

It's not possible to execute server config migration tests, even on the local machine. For the 15.0.x branch, the fix is already present, but for the 18.0.x not. For the upstream, the PR is created, but no additional responses are present, so I'll try to speed up the process in order to avoid those situations in the future.