Add Release Note (blurb): Following the [MSYS2 project](https://www.msys2.org/news/#2026-02-28-dropping-support-for-windows-81), on which Git for Windows is based, Windows 8.1 support will be dropped after Git for Windows v2.55.

Add Release Note (blurb): Following the [MSYS2 project](https://www.msys2.org/news/#2026-02-28-dropping-support-for-windows-81), on which Git for Windows is based, Windows 8.1 support will be dropped after Git for Windows v2.55. #259