Remove open-book References

[duichwer]

There are still wrong/old references to "open-book".

Wrong link to vulnerability report.

E-Mails to open-book.org

https://github.com/OkunaOrg/okuna-api/blob/master/CODE_OF_CONDUCT.md

https://github.com/OkunaOrg/okuna-api/blob/14976f6ea22fb796a1df7147f8481cfb597245d3/.env.sample#L68

Several here: https://github.com/OkunaOrg/okuna-api/blob/69599413f0966b5575dc24345ca143312d69b9ef/openbook_auth/tests/views/test_auth.py#L49

Old Api Name: https://github.com/OkunaOrg/okuna-api/blob/64ec6d112189dfd555e227181d1aa091ca8260b7/openbook/settings.py#L251

Foldername:

Consider renaming with git mv Don't know, if there would be problems with flutter.

[lifenautjoe]

API name and directories will have to remain the same. They're used by django to create database columns, tables and migrations. The rest, I have to verify the domain can be used by the API, tests don't matter much but a replace should do it.

Thanks!