v1.29.0

What's Changed

• Update loopback fw with sleep support by @robamu in #267
• Update loopback fw by @robamu in #238
• LED is_on and is_off do not require mutable access by @robamu in #265
• correction for HAL buttons book page by @robamu in #266
• Switch to probe-rs 0.31 by @jonathanpallant in #263

Full Changelog: v1.28.1...v1.29.0