Add a release workflow to GitHub Actions (astral-sh#257) 

Add GitHub Actions workflow 

pythonbuild: update default time in tar archives to 2024-01-01 Let's emit somewhat modern timestamps instead of times from 2021. The new date is midnight in UTC not midnight in US/Pacific.

unix: normalize build configuration to aid portability This commit implements a long desired feature to normalize the build configuration in various distribution files post build but pre packaging. The goal of this general feature is to make distributions highly portable. Before, configurations (which were used to e.g. compile extension modules) referenced build environment paths, like `/tools`. This is not desirable and can confuse downstream users when unexpected settings are used. The impetus for this work is astral-sh#194. As part of this change we strip the `-fdebug-default-version` argument from `CFLAGS` to restore CFLAGS compatibility with GCC. There's no doubt additional settings that could be normalized. Those can be implemented as follow-ups.

downloads: CPython 3.12.0rc3 -> 3.12.0 

downloads: CPython 3.11.4 -> 3.11.5 We remove a patch for limits.h handling because upstream incorporated a fix (from a bug report I filed). And it looks like upstream backported build system changes to build with OpenSSL 3.0 on Windows. We need to update our code accordingly. We really should be building against OpenSSL 3.0. But that's scope bloat. We'll get there.

requirements: update to latest 

downloads: upgrade LLVM toolchains 16.0.2 -> 16.0.3 

just: refactor macOS build script Builds still intermittently fail a lot for me. So let's retry the build once before giving up. To avoid repetition we use a shell for loop.

unix: always disable mkfifoat and mknodat on 3.8 Newer Apple SDKs say that these are introduced in macOS 13.0. So we need to ban them unconditionally on 3.8 since 3.8 doesn't support weak linking.