breeze-icons: add qtsvg as a propagatedBuildInput

pkgs/kde/frameworks/breeze-icons/default.nix

···
   mkKdeDerivation,
   python3,
   libxml2,
+  qtsvg,
 }:
 mkKdeDerivation {
   pname = "breeze-icons";
···
   extraNativeBuildInputs = [
     (python3.withPackages (ps: [ ps.lxml ]))
     libxml2
+  ];
+
+  # This package contains an SVG icon theme and an API forcing its use
+  extraPropagatedBuildInputs = [
+    qtsvg
   ];
 
   # lots of icons, takes forever, does absolutely nothing