Describe the doc issue

I propose to replace the Lena image of the tutorials by another image of set of images. Following the Losing Lena movement.

There is several problems with this image including:

• Sexualization: The Playboy magazine context implies that the original purpose of the image was to objectify and commodify women's bodies. Using this image as a benchmark may perpetuate these problematic attitudes towards women and their bodies
• Objectification and gender bias: The fact that the original image is of a woman in a sexualized pose raises concerns about objectification and gender bias. Using an image that perpetuates harmful gender stereotypes can reinforce existing power imbalances.
• Inclusivity: Related to the previous point, if it can avoid greasy laugh and display a better image of computer science, it's a winning change for everybody.
• It's not modern. The image is fifty years old now but the main problem is that it's de facto not a standard anymore. Many publishers systematically refuses articles with the image of Lena (including Nature, IEEE, Arxiv, a lot of US universities). Not using the Lena image is so more modern than using it, I think it's relevant considering the upcoming release of OpenCV 5.

Fix suggestion

To do this, I think it's more effective to remove it first from the tutorials then remove it from the tests (it's why I set this as a documentation issue).
I can do it myself and will publish a PR tomorrow about it (I already started it).

What do you think ?