Bump version to 5.7.1-dev (#1447)
Bump version to 5.7.1-dev (#1447)

Co-authored-by: GitHub Action <34eb4c4ef005207e8b8f916b9f1fffacccd6945e@github.com>
giantswarm/azure-operator,giantswarm/azure-operator,giantswarm/azure-operator