AppImage: Remove Qt.so to prevent importing from PyQt5.Qt

Importing from PyQt5.Qt is an unnecessary fallback that loads every PyQt5 module.

-----

taken from Electron-Cash/Electron-Cash@d69471b31d1f25a703588f48ee0cc5afdf1f1f2f

contrib/build-linux/appimage/build.sh

@@ -187,6 +187,8 @@ rm -rf "$APPDIR"/usr/lib/python3.6/site-packages/PyQt5/Qt/lib/libQt5Quick*
 rm -rf "$APPDIR"/usr/lib/python3.6/site-packages/PyQt5/Qt/lib/libQt5Location*
 rm -rf "$APPDIR"/usr/lib/python3.6/site-packages/PyQt5/Qt/lib/libQt5Test*
 rm -rf "$APPDIR"/usr/lib/python3.6/site-packages/PyQt5/Qt/lib/libQt5Xml*
+rm -rf "$APPDIR"/usr/lib/python3.6/site-packages/PyQt5/Qt.so
+
 
 # these are deleted as they were not deterministic; and are not needed anyway
 find "$APPDIR" -path '*/__pycache__*' -delete