qutebrowser: use pyqt6-webengine

pyqtwebengine uses qt5, but since qutebrowser 3.0.0 the derivation is
only building for qt6.

This is part of a goal to have no dependencies of qutebrowser marked as
broken.

pkgs/applications/networking/browsers/qutebrowser/default.nix

@@ -60,7 +60,7 @@ python3.pkgs.buildPythonApplication {
   ];
 
   propagatedBuildInputs = with python3.pkgs; ([
-    pyyaml pyqtwebengine jinja2 pygments
+    pyyaml pyqt6-webengine jinja2 pygments
     # scripts and userscripts libs
     tldextract beautifulsoup4
     readability-lxml pykeepass stem