Potential exposure of private data due to incorrect handling of Vary: * in UpdateCacheMiddleware

An issue was discovered in 6.0 before 6.0.5 and 5.2 before 5.2.14. `django.middleware.cache.UpdateCacheMiddleware` erroneously caches requests where the `Vary` header contained an asterisk (`'*'`). This can lead to private data being stored and served. 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 Ahmad Sadeddin for reporting this issue.