is that no need browsergym

### Bug Description

requirements.txt includes browsergym，but the code no import it，so is that need browsergym？

### Bug solved method

delete browsergym in requirement.txt 

### Environment information

- System version:
- Python version:
- OpenManus version or branch:
- Installation method (e.g., `pip install -r requirements.txt` or `pip install -e .`):


### Extra information

_No response_