Header injection possibility since DomainNameValidator accepted newlines in input

An issue was discovered in Django 6.0 before 6.0.7 and 5.2 before 5.2.16.

`DomainNameValidator` does not prohibit newlines in domain names (unless used via a form field, since `CharField` strips newlines). If an application uses values with newlines in an HTTP response, header injection can occur. Django itself is unaffected because `HttpResponse` prohibits newlines in HTTP headers.

Earlier, unsupported Django series (such as 5.0.x, 4.1.x, and 3.2.x) were not evaluated and may also be affected.

Django would like to thank Bence Nagy for reporting this issue.