Tests do not pass when just poetry text extras installed

[AshisGhosh]

System Info

Tested on `main`, commit: 1249aee

Information

• [X] One of the scripts in the examples/ folder of LeRobot
• [ ] My own task or dataset (give details below)

Reproduction

gym_pusht is a missing requirement.

1. Follow https://github.com/huggingface/lerobot/blob/main/CONTRIBUTING.md
2. Create a new conda env

conda create -y -n lerobot-dev python=3.10 && conda activate lerobot-dev

3. Install limited extras including test

poetry install --sync --extras "dev test"

4. Run all tests

DATA_DIR="tests/data" python -m pytest -sv ./tests

Received the following error:

>   ???
E   ModuleNotFoundError: No module named 'gym_pusht'

<string>:8: ModuleNotFoundError
========================================================= short test summary info ==========================================================
FAILED tests/test_examples.py::test_examples_3_and_2 - ModuleNotFoundError: No module named 'gym_pusht'
================================================ 1 failed, 39 passed, 25 skipped in 20.48s =================================================

Expected behavior

All tests to pass.