rekonq: fix homepage url

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

···
     platforms = platforms.linux;
     maintainers = [ maintainers.urkud ];
     description = "KDE Webkit browser";
-    homepage = http://rekonq.sourceforge.net;
+    homepage = https://rekonq.kde.org/;
   };
 }