* fix `LoadCertificate` unit test
replaced certificate with invalid dns name, which is rejected by stdlib of Go version >=1.25.2.
Change in Go introduced by https://github.com/golang/go/issues/75715
* code review: add script to generate certificates, remove `greenbone` org entry
* code review: add license header
* rework cert creation and fix one filename
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Co-authored-by: Marius Goetze <marius.goetze@greenbone.net>
