Most probably you ran pip3 install something, and that pulled in PyQt5. Check what else is in your /home/marco/.local/lib/python3.5/site-packages/ and in /home/marco/.local/bin/ and you will see what it was.
Most probably you ran pip3 install something, and that pulled in PyQt5. Check what else is in your /home/marco/ .local/ lib/python3. 5/site- packages/ and in /home/marco/ .local/ bin/ and you will see what it was.