Release of libvirt-php-0.5.6

[Michal Prívozník]

The 0.5.6 release of libvirt-php is tagged and tarball is available at:

https://libvirt.org/sources/php/

Notable changes:

* PHP-8.0 support
* Implemented virDomainSnapshotCurrent() API
* Implemented virNetworkGetDHCPLeases() API
* Implemented virDomainGetCPUStats() API
* Implemented virDomainUndefineFlags() API
* Fixed libvirt_domain_interface_addresses() when multiple addresses are
reported
* Bug fixes

Thanks to everybody who helped with this release.

Michal