title: Python - pyqt xcb plugin with thread error
body: <p>I am using Ubuntu, when I run my program from pyqt, I got this error,</p>
  <pre><code>QObject::moveToThread: Current thread (0xa549e0) is not the object's thread (0x4b7bfc0).
  Cannot move to target thread (0xa549e0)
  
  qt.qpa.plugin: Could not load the Qt platform plugin &quot;xcb&quot; in &quot;/home/mialo/.local/lib/python3.8/site-packages/cv2/qt/plugins&quot; even though it was found.
  This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.
  
  Available platform plugins are: xcb, eglfs, linuxfb, minimal, minimalegl, offscreen, vnc, wayland-egl, wayland, wayland-xcomposite-egl, wayland-xcomposite-glx, webgl.
  
  Aborted (core dumped)
  </code></pre>
  <p><code>pip3 list|grep Qt</code> for this command, I got</p>
  <pre><code>PyQt5                        5.15.5              
  PyQt5-Qt5                    5.15.2              
  PyQt5-sip                    12.9.0              
  QtPy                         1.11.1   
  </code></pre>
  <p>I tried many solutions from uninstalling opencv-python and installig opencv-headless, <code>export DISPLAY=:1.0</code> etc</p>
  <p>But nothing worked, what should we do to solve this issue,</p>
  <p>thanks</p>