Use opencv-python-headless instead of opencv-python as a dependency

[helpmefindaname]

🚀 The feature

Loosen up the dependencies by only requiring the headless version of opencv

Motivation, pitch

Similar to onnxtr https://github.com/felixdittrich92/OnnxTR/blob/main/pyproject.toml#L64 it would be good to have an option to only install the headless version of opencv. As this project doesn't explicitely use opencv-gui anywhere, it shouldn't require to install the gui-libraries.

Alternatives

No response

Additional context

No response

[felixdittrich92]

Hi @helpmefindaname 👋,

I understand the need, but most other libraries rely on opencv-python rather than the headless version.
Since version 1.0.0, after dropping TensorFlow support, we’ve been happy to have doctr installable in a single way, without the [tf] / [torch] extras. Introducing this change would break that consistency again.

For OnnxTR, the focus is really on production systems, where such options make sense. If you really need this for doctr, I think it would be better to uninstall opencv-python after installing doctr and then install the headless version instead.

Wdyt ?