brew says outdated when I upgrade to latest version

% brew search postgresql ==> Formulae postgresql@10 postgresql@11 postgresql@12 postgresql@13 postgresql@14 postgresql@15 postgresql@16 qt-postgresql postgrest % brew install postgresql@16 Warning: You are using macOS 11. We (and Apple) do not provide support for this old version. It is expected behaviour that some formulae will fail to build in this old version. It is expected behaviour that Homebrew will be buggy and slow. Do not create any issues about this on Homebrew's GitHub repositories. Do not create any issues even if you think this message is unrelated. Any opened issues will be immediately closed without response. Do not ask for help from Homebrew or its maintainers on social media. You may ask for help in Homebrew's discussions but are unlikely to receive a response. Try to figure out the problem yourself and submit a fix as a pull request. We will review it but may or may not accept it. Okay, so I'm in murky waters here. But help me understand what the message means. Is it complaining that my chosen version of postgresql (the latest, from all I can see) is too far out of date, or that my Mac OS version is too far out of date? (I'm on MacOS 11.6 Big Sur) The install ends with the following. Likely related, or unrelated? ==> Fetching postgresql@16 ==> Downloading https://ghcr.io/v2/homebrew/core/postgresql/16/blobs/sha256:00985f8cf5b7b9b9adb52fa7d201e188310ce11210d9820efa2295344aed3 ################################################################################################################################## 100.0% ==> Installing dependencies for postgresql@16: gettext and krb5 Error: Cannot link gettext Another version is already linked: /usr/local/Cellar/gettext/0.21