[Development] Qt Project Release team decision: no Qt 5.6.4 release

[Jani Heikkinen]

Hi!

Qt Project Release team has now officially agreed that there won't be Qt 5.6.4 release anymore even support for Qt 5.6 series continues until March 2019 as planned (see release team memo here: https://lists.qt-project.org/pipermail/releasing/2018-November/004703.html).
We will keep the branch open for backports of REALLY important things until March 2019.

br,
Jani Heikkinen
Release Manager