Inkscape icon does not show up on taskbar when running it from install_dir
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#### Steps to reproduce:
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if you are a developer you might know the steps already. It happens when testing the changes,
- open the application on terminal by navigating to build directory then run install_dir/bin/inkscape
- inkscape window will open
#### What happened?
The opened application functions like it should but it's [icon](https://cdn.iconscout.com/icon/free/png-512/inkscape-569205.png) isn't visible on the taskbar.
#### What should have happened?
The icon should have showed itself (I am not sure if that is supposed to happen or not but blank looks weird)
#### Inkscape Version and Operating System:
- Operating System: Ubuntu
- Operating System version: 20.04

issue