Update camera.md

[galou]

Fix the documentation of the return type of getImage() in Python. Add typing hints.

Description Fix the documentation of the return type of getImage() in Python. Add typing hints.

Related Issues Wrong documentation.

Tasks Add the list of tasks of this PR.

• [x] Update the documentation (if needed)

Documentation If this pull-request changes the doc, add the link to the related page, including the ?version=BRANCH_NAME, such as: https://cyberbotics.com/doc/guide/getting-started-with-webots?version=galou:getimage_returns_bytes