Because it comes from upstream, and it's preferable to use the upstream source directly instead of adding an image file to AUR. You can use this URL as source for the icon:
http://osp.kitchen/static/img/OSP_new-frog.svg

@City-busz, done
can you elaborate about the icon file, why would i remove it from package ? what's bad with it ?

@City-busz
ok i'll do that !

Please make the following changes:
- Remove the included 'ospkit.png' file, and grab it from the archive or download from the internet.
- Replace arch=('any') with arch=('i686' 'x86_64'), because it contains architecture-dependent binary.
- Move qt5-webkit from makedepends to depends, because it's needed for the binary on runtime.
- Add PREFIX=/usr as parameter for qmake to avoid insecure rpath.