message: [contour] Replace qImage.mirror() with qImage = qImage.mirrored() to also compile on Qt 5.
diff: @@ -911,8 +911,9 @@ void OpenGLRenderer::setBackgroundImage(shared_ptr<terminal::BackgroundImage con
  DisplayLog()("Background image from disk: {}x{} {}", qImage.width(), qImage.height(), imageFormat);
  _renderStateCache.backgroundImageHash = crispy::StrongHash::compute(filePath.string());
  _renderStateCache.backgroundResolution = qImage.size();
  - // for glTextImage2D image must be inverted
  - qImage.mirror();
  + // For glTextImage2D image must be inverted.
  + // TODO: This can be rewritten to `qImage.mirror();` as soon as we drop Qt 5.
  + qImage = qImage.mirrored();
  _backgroundImageTexture =
  createAndUploadImage(qImage.size(), imageFormat, rowAlignment, qImage.constBits());
  }
  