Release v3.1.0a4

Added

• Enabled builtin bytearray (pull#60).
• Enabled ustruct module (pull#60).
• Added alpha support for dual boot installation on the SPIKE Prime Hub.
• Added pybricks.experimental.hello_world function to make it easier for
  new contributors to experiment with Pybricks using C code.
• Added ability to import the main.mpy that is embedded in the firmware from
  a download and run program (support#408).
• Added pybricks.iodevices.LWP3Device to communicate with a device that supports
  the LEGO Wireless Protocol 3.0.00 (pull#68)

Changed

• Move Hub Bluetooth optimizations to reduce firmware size (issue#49).
• Disabled pybricks.iodevices module on Move Hub to reduce firmware size.
• Improvements to pybricks.pupdevices.Remote:
  • Check if a remote is already connected before attempting to create a new
    connection.
  • Rename first argument from address to name to match documentation.
  • Implement connecting by name.
  • Add name() method.
  • Add light attribute.