[KStopmotion] Stopmotion release 0.8.6

[Christoph Grüninger]

Dear Stopmotion users and developers,

yesterday I tagged the master branch to be stopmotion release 0.8.6.
https://invent.kde.org/multimedia/stopmotion/-/releases/0.8.6

This is the first release under the KDE umbrella.
* New build system using CMake. The qmake one is deprecated and
   will be removed.
* The test test-stopmotion can be executed as a CMake test target
   (`make test-stopmotion && make test).
* Fixed various warnings from Clang, GCC, and Qt 5.15.
* We have a build pipeline executing automated builds and tests.

I prepared an update for the openSuse's stopmotion package and I am 
going to forward this email to Debian's stopmotion package maintainer. I 
will write a blog entry for Planet KDE to get more visibility.

For the upcoming release, I plan to remove the deprecated qmake build 
system, use some of the KDE libraries, rename it from Linux-Stopmotion 
to KStopmotion, and investigate what is needed to be done to switch to Qt 6.

Bye
Christoph