installation error encountered on windows WSL

Hi,

I ran the following command to install FinRL:

```
pip install git+https://github.com/AI4Finance-Foundation/FinRL.git

```

However, the following error occurred:

```
error: subprocess-exited-with-error

× python setup.py egg_info did not run successfully.
│ exit code: 1
╰─> [1 lines of output]
error in gym setup command: 'extras_require' must be a dictionary whose values are strings or lists of strings containing valid project/version requirement specifiers.
[end of output]

note: This error originates from a subprocess, and is likely not a problem with pip.
error: metadata-generation-failed

× Encountered error while generating package metadata.
╰─> See above for output.

note: This is an issue with the package mentioned above, not pip.
hint: See above for details.

```

I did some googling but was not able to fix this yet. Any help is greatly appreciated!