Installing environments via pixi fails

[akhilsathuluri]

1. Currently the tag used for environments is not recognised by pixi and needs to be modified to tool.pixi.environments instead of just environment. Throws error,

  ⚠ The feature 'drake' is defined but not used in any environment
    ╭─[/home/wslaniakea/git/comodo/pyproject.toml:78:20]
 77 │
 78 │ [tool.pixi.feature.drake.pypi-dependencies]
    ·                    ─────
 79 │ drake = ">=1.34.0, <2"
    ╰────
  help: Remove the feature from the manifest or add it to an environment


  ⚠ The feature 'hippopt' is defined but not used in any environment
    ╭─[/home/wslaniakea/git/comodo/pyproject.toml:86:20]
 85 │
 86 │ [tool.pixi.feature.hippopt.dependencies]
    ·                    ───────
 87 │ liecasadi = "*"
    ╰────
  help: Remove the feature from the manifest or add it to an environment

Error:
  × unknown environment 'drake'

2. Installing the env throws ffmpeg-python not found error since there is a typo

  × failed to solve the conda requirements of 'default' 'linux-64'
  ╰─▶ Cannot solve the request because of: No candidates were found for ffmepg-python *.

3. Running the jaxsim examples cause error that integrators cannot be imported. Removing the import since its not used fixes this issue.