The 5.6.0 directory exists on windows.php.net since February 22 but it's empty:

The fact that https://pecl.php.net/rest/r/sqlsrv/stable.txt points to 5.6.0 breaks build automation (e.g. on doctrine/dbal).

One of the published build logs contains:

C:\php-snap-build\php-src\php71\x64\php-src\configure.js(5499, 13) Microsoft JScript runtime error: 'PHP_PDO_SQLSRV' is undefined