[horde] Alpha Tags for PHP 8 versions (maintaina)

[Ralf Lang]

Hello,

at the moment a lot of packages on the satis repository only have tagged 
alpha releases for PHP 7. This means PHP 8 must be run directly off the 
development branch FRAMEWORK_6_0. This is undesirable.
This weekend I will ensure that there is a current, alpha-tagged version 
of all required packages for horde base and the core groupware/webmail 
apps. I will probably leave out some less commonly used packages.
As a result, groupware will be able to run on PHP 8.1 with 
minimum-stability tag raised to alpha. The 
https://github.com/maintaina-com/horde-deployment repo will subsequently 
be changed to use that setting.