v0.4: UpkieServosEnv environment

[stephane-caron]

This release adds the UpkieServosEnv environment, with full observations and joint position-velocity-torque control. It also brings a regular batch of fixes and improvements to the Pink and PPO balancers.

Added

• Environment: UpkieServosEnv-v1
• PPO balancer: distribute sample policy
• Pink balancer: --visualize argument
• Spine: Air Bullet, same as Bullet but floating in the air
• Utils: Pinocchio utility functions

Changed

• Load description from local package rather than cloning a repository
• Rename UpkieWheelsReward to StandingReward

Fixed

• UpkieWheelsEnv: observation limits for ground position and velocity
• Pink balancer: reduce LM damping to fix stalling when crouching
• PPO balancer: get environment id (thanks @Varun-GP)

---

This discussion was created from the release v0.4.0.