Add QWebKit Compile Option to CI Matrix

[sieren]

Should add the QWebKit Compile Time option to the Build Matrix to make sure we dont break anything during updates.

[marco-m]

In my experience, maintaining compile-time options is always a lot of pain, to be done only if really necessary, so the question: since the same functionality is provided in the default build with QWebEngine, why not simply getting rid of the QWebKit option completely? :-)

Look at it also from a pragmatic point of view: this ticket is 7 months old, it looks like there are not enough resources to properly maintain it...

Quoting Saint-Exupéry: "perfection is finally attained not when there is no longer anything to add, but when there is no longer anything to take away ..."

😄

[sieren]

I'd like to keep both in there for now, mainly because QtWebEngine on Debian is quite cumbersome to get running (see #138 & #145). The Interface of both classes abstracting WebKit/WebEngine in QST is identical, but on occasion I've forgotten to update either one of them leading to a break. I suppose it's only a matter of a minute to actually add this to CI ;) I really should do that, but I'm more exciting about working on the UI overhaul right now ;)