Release of libvirt-7.5.0

[Jiri Denemark]

The 7.5.0 release of both libvirt and libvirt-python is tagged and
signed tarballs and source RPMs are available at

    https://libvirt.org/sources/
    https://libvirt.org/sources/python/

Thanks everybody who helped with this release by sending patches,
reviewing, testing, or providing any other feedback. Your work is
greatly appreciated.

* Security

  * svirt: fix MCS label generation (CVE-2021-3631)

    A flaw in the way MCS labels were generated could result in a VM's
    resource not being fully protected from access by another VM were
    it to be compromised. https://gitlab.com/libvirt/libvirt/-/issues/153

* Removed features

  * xen: Remove support for Xen < 4.9

    In accordance with our platform support policy, the oldest supported Xen
    version is now bumped from 4.6 to 4.9.

* Improvements

  * docs: Document disk serial truncation status quo

    Disk ``<serial>`` is being truncated by QEMU before passed to the guest.
    Since it's impossible to fix it without running into further regressions
    the documentation was improved to document the intricacies.

* Bug fixes

  * qemu: Fixed validation of disk ``iothread`` configuration

    The validation of ``iothread`` config was previously moved to a place where
    it caused bogus errors when address wasn't allocated when hotplugging a
    disk. The check is now removed as it wasn't actually necessary at all.

Enjoy.

Jirka