Uncomment `pypi-versions-badge` from README.md.
Uncomment `pypi-versions-badge` from README.md.

This badge now works correctly since version 2.2.1 has been uploaded to PyPI.

PiperOrigin-RevId: 461476606
Change-Id: I22b40d2fbf900a7cbd86b04f7af69c313bcc721d

deepmind/mujoco,deepmind/mujoco,deepmind/mujoco,deepmind/mujoco,deepmind/mujoco